Gen
GR
SP
Dens
Log
Interpretation
Charts
2013 Edition
Neu
NMR
RLl
RInd
REm
Rt
Lith
Por
SatOH
SatCH
Perm
Cem
Schlumberger
3750 Briarpark Drive
Houston, Texas 77042
www.slb.com
© 2013 Schlumberger. All rights reserved.
No part of this book may be reproduced, stored
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Specifications are current at the time of printing.
13-FE-0034
ISBN-13: 978-1-937949-10-5
An asterisk (*) is used throughout this document to
denote a mark of Schlumberger.
Contents
Contents
Foreword................................................................................................................................................................................................................................................................... xi
General
Symbols Used in Log Interpretation..................................................................................................................................................... Gen-1........................................ 1
Estimation of Formation Temperature with Depth......................................................................................................................... Gen-2........................................ 3
Estimation of Rmf and Rmc........................................................................................................................................................................ Gen-3........................................ 4
Equivalent NaCl Salinity of Salts........................................................................................................................................................... Gen-4........................................ 5
Concentration of NaCl Solutions........................................................................................................................................................... Gen-5........................................ 6
Resistivity of NaCl Water Solutions....................................................................................................................................................... Gen-6........................................ 8
Density of Water and Hydrogen Index of Water and Hydrocarbons .......................................................................................... Gen-7........................................ 9
Density and Hydrogen Index of Natural Gas...................................................................................................................................... Gen-8...................................... 10
Sound Velocity of Hydrocarbons............................................................................................................................................................ Gen-9...................................... 11
Gas Effect on Compressional Slowness............................................................................................................................................... Gen-9a.................................... 12
Gas Effect on Acoustic Velocity.............................................................................................................................................................. Gen-9b.................................... 13
Nuclear Magnetic Resonance Relaxation Times of Water............................................................................................................. Gen-10.................................... 14
Nuclear Magnetic Resonance Relaxation Times of Hydrocarbons............................................................................................. Gen-11a................................. 15
Nuclear Magnetic Resonance Relaxation Times of Hydrocarbons............................................................................................. Gen-11b................................. 16
Capture Cross Section of NaCl Water Solutions............................................................................................................................... Gen-12.................................... 18
Capture Cross Section of NaCl Water Solutions............................................................................................................................... Gen-13.................................... 19
Capture Cross Section of Hydrocarbons.............................................................................................................................................. Gen-14.................................... 21
EPT* Propagation Time of NaCl Water Solutions............................................................................................................................. Gen-15.................................... 22
EPT Attenuation of NaCl Water Solutions.......................................................................................................................................... Gen-16.................................... 23
EPT Propagation Time–Attenuation Crossplot................................................................................................................................ Gen-16a................................. 24
Gamma Ray
Scintillation Gamma Ray—33⁄8- and 111⁄16-in. Tools............................................................................................................................ GR-1........................................ 25
Scintillation Gamma Ray—33⁄8- and 111⁄16-in. Tools............................................................................................................................ GR-2........................................ 26
Scintillation Gamma Ray—33⁄8- and 111⁄16-in. Tools............................................................................................................................ GR-3........................................ 27
SlimPulse* and E-Pulse* Gamma Ray Tools...................................................................................................................................... GR-6........................................ 28
ImPulse* Gamma Ray—4.75-in. Tool................................................................................................................................................... GR-7........................................ 29
PowerPulse* and TeleScope* Gamma Ray—6.75-in. Tools.......................................................................................................... GR-9........................................ 30
PowerPulse Gamma Ray—8.25-in. Normal-Flow Tool.................................................................................................................... GR-10..................................... 31
PowerPulse Gamma Ray—8.25-in. High-Flow Tool......................................................................................................................... GR-11..................................... 32
PowerPulse Gamma Ray—9-in. Tool.................................................................................................................................................... GR-12..................................... 33
PowerPulse Gamma Ray—9.5-in. Normal-Flow Tool...................................................................................................................... GR-13..................................... 34
PowerPulse Gamma Ray—9.5-in. High-Flow Tool........................................................................................................................... GR-14..................................... 35
geoVISION675* GVR* Gamma Ray—6.75-in. Tool........................................................................................................................... GR-15..................................... 36
RAB* Gamma Ray—8.25-in. Tool.......................................................................................................................................................... GR-16..................................... 37
arcVISION475* Gamma Ray—4.75-in. Tool....................................................................................................................................... GR-19..................................... 38
iii
Contents
arcVISION675* Gamma Ray—6.75-in. Tool....................................................................................................................................... GR-20..................................... 39
arcVISION825* Gamma Ray—8.25-in. Tool....................................................................................................................................... GR-21..................................... 40
arcVISION900* Gamma Ray—9-in. Tool............................................................................................................................................. GR-22..................................... 41
arcVISION475 Gamma Ray—4.75-in. Tool......................................................................................................................................... GR-23..................................... 42
arcVISION675 Gamma Ray—6.75-in. Tool......................................................................................................................................... GR-24..................................... 43
arcVISION825 Gamma Ray—8.25-in. Tool......................................................................................................................................... GR-25..................................... 44
arcVISION900 Gamma Ray—9-in. Tool............................................................................................................................................... GR-26..................................... 45
EcoScope* Integrated LWD Gamma Ray—6.75-in. Tool............................................................................................................... GR-27..................................... 46
EcoScope Integrated LWD Gamma Ray—6.75-in. Tool................................................................................................................. GR-28..................................... 47
Spontaneous Potential
Rweq Determination from ESSP................................................................................................................................................................ SP-1......................................... 49
Rweq versus Rw and Formation Temperature..................................................................................................................................... SP-2......................................... 50
Rweq versus Rw and Formation Temperature..................................................................................................................................... SP-3......................................... 51
Bed Thickness Correction—Open Hole.............................................................................................................................................. SP-4......................................... 53
Bed Thickness Correction—Open Hole (Empirical)...................................................................................................................... SP-5......................................... 54
Bed Thickness Correction—Open Hole (Empirical)...................................................................................................................... SP-6......................................... 55
Density
Porosity Effect on Photoelectric Cross Section................................................................................................................................ Dens-1.................................... 56
Apparent Log Density to True Bulk Density....................................................................................................................................... Dens-2.................................... 57
Neutron
Dual-Spacing Compensated Neutron Tool Charts.............................................................................................................................................................................. 58
Compensated Neutron Tool..................................................................................................................................................................... Neu-1...................................... 60
Compensated Neutron Tool..................................................................................................................................................................... Neu-2...................................... 61
Compensated Neutron Tool..................................................................................................................................................................... Neu-3...................................... 63
Compensated Neutron Tool..................................................................................................................................................................... Neu-4...................................... 64
Compensated Neutron Tool..................................................................................................................................................................... Neu-5...................................... 65
Compensated Neutron Tool..................................................................................................................................................................... Neu-6...................................... 67
Compensated Neutron Tool..................................................................................................................................................................... Neu-7...................................... 69
Compensated Neutron Tool..................................................................................................................................................................... Neu-8...................................... 71
Compensated Neutron Tool..................................................................................................................................................................... Neu-9...................................... 73
APS* Accelerator Porosity Sonde.......................................................................................................................................................... Neu-10.................................... 75
APS Accelerator Porosity Sonde Without Environmental Corrections..................................................................................... Neu-11.................................... 76
CDN* Compensated Density Neutron, adnVISION* Azimuthal Density
Neutron, and EcoScope* Integrated LWD Tools............................................................................................................................... Neu-30.................................... 78
adnVISION475* Azimuthal Density Neutron—4.75-in. Tool and 6-in. Borehole................................................................... Neu-31.................................... 80
adnVISION475 BIP Neutron—4.75-in. Tool and 6-in. Borehole.................................................................................................. Neu-32.................................... 81
adnVISION475 Azimuthal Density Neutron—4.75-in. Tool and 8-in. Borehole..................................................................... Neu-33.................................... 82
adnVISION475 BIP Neutron—4.75-in. Tool and 8-in. Borehole.................................................................................................. Neu-34.................................... 83
iv
Contents
adnVISION675* Azimuthal Density Neutron—6.75-in. Tool and 8-in. Borehole................................................................... Neu-35.................................... 84
adnVISION675 BIP Neutron—6.75-in. Tool and 8-in. Borehole.................................................................................................. Neu-36.................................... 85
adnVISION675 Azimuthal Density Neutron—6.75-in. Tool and 10-in. Borehole................................................................... Neu-37.................................... 86
adnVISION675 BIP Neutron—6.75-in. Tool and 10-in. Borehole................................................................................................ Neu-38.................................... 87
adnVISION825* Azimuthal Density Neutron—8.25-in. Tool and 12.25-in. Borehole........................................................... Neu-39.................................... 88
CDN Compensated Density Neutron and adnVISION825s* Azimuthal Density Neutron—
8-in. Tool and 12-in. Borehole................................................................................................................................................................. Neu-40.................................... 89
CDN Compensated Density Neutron and adnVISION825s Azimuthal Density Neutron—
8-in. Tool and 14-in. Borehole................................................................................................................................................................. Neu-41.................................... 90
CDN Compensated Density Neutron and adnVISION825s Azimuthal Density Neutron—
8-in. Tool and 16-in. Borehole................................................................................................................................................................. Neu-42.................................... 91
EcoScope* Integrated LWD BPHI Porosity—6.75-in. Tool and 8.5-in. Borehole................................................................... Neu-43.................................... 93
EcoScope Integrated LWD BPHI Porosity—6.75-in. Tool and 9.5-in. Borehole..................................................................... Neu-44.................................... 94
EcoScope Integrated LWD TNPH Porosity—6.75-in. Tool and 8.5-in. Borehole.................................................................... Neu-45.................................... 95
EcoScope Integrated LWD TNPH Porosity—6.75-in. Tool and 9.5-in. Borehole.................................................................... Neu-46.................................... 96
EcoScope Integrated LWD—6.75-in. Tool.......................................................................................................................................... Neu-47.................................... 98
Nuclear Magnetic Resonance
CMR* Tool..................................................................................................................................................................................................... CMR-1.................................... 99
Resistivity Laterolog
ARI* Azimuthal Resistivity Imager....................................................................................................................................................... RLl-1.....................................101
High-Resolution Azimuthal Laterolog Sonde (HALS).................................................................................................................... RLl-2.....................................102
High-Resolution Azimuthal Laterolog Sonde (HALS).................................................................................................................... RLl-3.....................................103
High-Resolution Azimuthal Laterolog Sonde (HALS).................................................................................................................... RLl-4.....................................104
High-Resolution Azimuthal Laterolog Sonde (HALS).................................................................................................................... RLl-5.....................................105
High-Resolution Azimuthal Laterolog Sonde (HALS).................................................................................................................... RLl-6.....................................106
High-Resolution Azimuthal Laterolog Sonde (HALS).................................................................................................................... RLl-7.....................................107
High-Resolution Azimuthal Laterolog Sonde (HALS).................................................................................................................... RLl-8.....................................108
High-Resolution Azimuthal Laterolog Sonde (HALS).................................................................................................................... RLl-9.....................................109
HRLA* High-Resolution Laterolog Array............................................................................................................................................ RLl-10..................................110
HRLA High-Resolution Laterolog Array............................................................................................................................................... RLl-11..................................111
HRLA High-Resolution Laterolog Array............................................................................................................................................... RLl-12..................................112
HRLA High-Resolution Laterolog Array............................................................................................................................................... RLl-13..................................113
HRLA High-Resolution Laterolog Array............................................................................................................................................... RLl-14..................................114
GeoSteering* Bit Resistivity—6.75-in. Tool....................................................................................................................................... RLl-20..................................115
GeoSteering arcVISION675 Resistivity—6.75-in. Tool................................................................................................................... RLl-21..................................116
GeoSteering Bit Resistivity in Reaming Mode—6.75-in. Tool...................................................................................................... RLl-22..................................117
geoVISION* Resistivity Sub—6.75-in. Tool........................................................................................................................................ RLl-23..................................118
geoVISION Resistivity Sub—8.25-in. Tool.......................................................................................................................................... RLl-24..................................119
GeoSteering Bit Resistivity—6.75-in. Tool......................................................................................................................................... RLl-25..................................120
v
Contents
CHFR* Cased Hole Formation Resistivity Tool................................................................................................................................. RLl-50..................................121
CHFR Cased Hole Formation Resistivity Tool................................................................................................................................... RLl-51..................................122
CHFR Cased Hole Formation Resistivity Tool................................................................................................................................... RLl-52..................................123
Resistivity Induction
AIT* Array Induction Imager Tool........................................................................................................................................................ RInd-1..................................125
AIT Array Induction Imager Tool..........................................................................................................................................................................................................126
Resistivity Electromagnetic
arcVISION475 and ImPulse 43⁄4-in. Array Resistivity Compensated Tools—2 MHz ............................................................. REm-11................................131
arcVISION475 and ImPulse 43⁄4-in. Array Resistivity Compensated Tools—2 MHz ............................................................. REm-12................................132
arcVISION475 and ImPulse 43⁄4-in. Array Resistivity Compensated Tools—2 MHz ............................................................. REm-13................................133
arcVISION475 and ImPulse 43⁄4-in. Array Resistivity Compensated Tools—2 MHz ............................................................. REm-14................................134
arcVISION675 63⁄4-in. Array Resistivity Compensated Tool—400 kHz...................................................................................... REm-15................................135
arcVISION675 63⁄4-in. Array Resistivity Compensated Tool—400 kHz...................................................................................... REm-16................................136
arcVISION675 63⁄4-in. Array Resistivity Compensated Tool—400 kHz...................................................................................... REm-17................................137
arcVISION675 63⁄4-in. Array Resistivity Compensated Tool—400 kHz...................................................................................... REm-18................................138
arcVISION675 63⁄4-in. Array Resistivity Compensated Tool—2 MHz......................................................................................... REm-19................................139
arcVISION675 63⁄4-in. Array Resistivity Compensated Tool—2 MHz........................................................................................... REm-20................................140
arcVISION675 63⁄4-in. Array Resistivity Compensated Tool—2 MHz........................................................................................... REm-21................................141
arcVISION675 63⁄4-in. Array Resistivity Compensated Tool—2 MHz........................................................................................... REm-22................................142
arcVISION825 81⁄4-in. Array Resistivity Compensated Tool—400 kHz....................................................................................... REm-23................................143
arcVISION825 81⁄4-in. Array Resistivity Compensated Tool—400 kHz....................................................................................... REm-24................................144
arcVISION825 81⁄4-in. Array Resistivity Compensated Tool—400 kHz....................................................................................... REm-25................................145
arcVISION825 81⁄4-in. Array Resistivity Compensated Tool—400 kHz....................................................................................... REm-26................................146
arcVISION825 81⁄4-in. Array Resistivity Compensated Tool—2 MHz........................................................................................... REm-27................................147
arcVISION825 81⁄4-in. Array Resistivity Compensated Tool—2 MHz........................................................................................... REm-28................................148
arcVISION825 81⁄4-in. Array Resistivity Compensated Tool—2 MHz........................................................................................... REm-29................................149
arcVISION825 81⁄4-in. Array Resistivity Compensated Tool—2 MHz........................................................................................... REm-30................................150
arcVISION900 9-in. Array Resistivity Compensated Tool—400 kHz.......................................................................................... REm-31................................151
arcVISION900 9-in. Array Resistivity Compensated Tool—400 kHz.......................................................................................... REm-32................................152
arcVISION900 9-in. Array Resistivity Compensated Tool—400 kHz.......................................................................................... REm-33................................153
arcVISION900 9-in. Array Resistivity Compensated Tool—400 kHz.......................................................................................... REm-34................................154
arcVISION900 9-in. Array Resistivity Compensated Tool—2 MHz............................................................................................. REm-35................................155
arcVISION900 9-in. Array Resistivity Compensated Tool—2 MHz............................................................................................. REm-36................................156
arcVISION900 9-in. Array Resistivity Compensated Tool—2 MHz............................................................................................. REm-37................................157
vi
Contents
arcVISION900 9-in. Array Resistivity Compensated Tool—2 MHz............................................................................................. REm-38................................158
arcVISION675, arcVISION825, and arcVISION900 Array Resistivity Compensated Tools—400 kHz.............................. REm-55................................160
arcVISION and ImPulse Array Resistivity Compensated Tools—2 MHz.................................................................................. REm-56................................161
arcVISION675 and ImPulse Array Resistivity Compensated Tools—2 MHz and 16-in. Spacing...................................... REm-58................................162
arcVISION675 and ImPulse Array Resistivity Compensated Tools—2 MHz and 22-in. Spacing...................................... REm-59................................163
arcVISION675 and ImPulse Array Resistivity Compensated Tools—2 MHz and 28-in. Spacing...................................... REm-60................................164
arcVISION675 and ImPulse Array Resistivity Compensated Tools—2 MHz and 34-in. Spacing...................................... REm-61................................165
arcVISION675 and ImPulse Array Resistivity Compensated Tools—2 MHz and 40-in. Spacing...................................... REm-62................................166
arcVISION675 and ImPulse Array Resistivity Compensated Tools—2 MHz with Dielectric Assumption..................... REm-63................................167
Formation Resistivity
Resistivity Galvanic.................................................................................................................................................................................... Rt-1.......................................168
High-Resolution Azimuthal Laterlog Sonde (HALS)....................................................................................................................... Rt-2.......................................169
High-Resolution Azimuthal Laterlog Sonde (HALS)....................................................................................................................... Rt-3.......................................170
geoVISION675* Resistivity....................................................................................................................................................................... Rt-10.....................................171
geoVISION675 Resistivity......................................................................................................................................................................... Rt-11.....................................172
geoVISION675 Resistivity......................................................................................................................................................................... Rt-12.....................................173
geoVISION675 Resistivity......................................................................................................................................................................... Rt-13.....................................174
geoVISION825* 81⁄4-in. Resistivity-at-the-Bit Tool............................................................................................................................. Rt-14.....................................175
geoVISION825 81⁄4-in. Resistivity-at-the-Bit Tool............................................................................................................................... Rt-15.....................................176
geoVISION825 81⁄4-in. Resistivity-at-the-Bit Tool............................................................................................................................... Rt-16.....................................177
geoVISION825 81⁄4-in. Resistivity-at-the-Bit Tool............................................................................................................................... Rt-17.....................................178
arcVISION Array Resistivity Compensated Tool—400 kHz.......................................................................................................... Rt-31.....................................179
arcVISION and ImPulse Array Resistivity Compensated Tools—2 MHz.................................................................................. Rt-32.....................................180
arcVISION Array Resistivity Compensated Tool—400 kHz.......................................................................................................... Rt-33.....................................181
arcVISION and ImPulse Array Resistivity Compensated Tools—2 MHz.................................................................................. Rt-34.....................................182
arcVISION Array Resistivity Compensated Tool—400 kHz.......................................................................................................... Rt-35.....................................183
arcVISION and ImPulse Array Resistivity Compensated Tools—2 MHz.................................................................................. Rt-36.....................................184
arcVISION675 Array Resistivity Compensated Tool—400 kHz.................................................................................................... Rt-37.....................................185
arcVISION675 and ImPulse Array Resistivity Compensated Tools—2 MHz........................................................................... Rt-38.....................................186
arcVISION Array Resistivity Compensated Tool—400 kHz.......................................................................................................... Rt-39.....................................187
arcVISION and ImPulse Array Resistivity Compensated Tools—2 MHz.................................................................................. Rt-40.....................................188
arcVISION Array Resistivity Compensated Tool—400 kHz in Horizontal Well...................................................................... Rt-41.....................................190
arcVISION and ImPulse Array Resistivity Compensated Tools—2 MHz in Horizontal Well.............................................. Rt-42.....................................191
vii
Contents
Lithology
Density and NGS* Natural Gamma Ray Spectrometry Tool.......................................................................................................... Lith-1....................................193
NGS Natural Gamma Ray Spectrometry Tool.................................................................................................................................... Lith-2....................................194
Platform Express* Three-Detector Lithology Density Tool........................................................................................................... Lith-3....................................196
Platform Express Three-Detector Lithology Density Tool............................................................................................................. Lith-4....................................197
Density Tool.................................................................................................................................................................................................. Lith-5....................................198
Density Tool.................................................................................................................................................................................................. Lith-6....................................200
Environmentally Corrected Neutron Curves...................................................................................................................................... Lith-7....................................202
Environmentally Corrected APS Curves.............................................................................................................................................. Lith-8....................................204
Bulk Density or Interval Transit Time and Apparent Total Porosity......................................................................................... Lith-9....................................206
Bulk Density or Interval Transit Time and Apparent Total Porosity......................................................................................... Lith-10.................................207
Density Tool.................................................................................................................................................................................................. Lith-11.................................209
Density Tool.................................................................................................................................................................................................. Lith-12.................................210
Porosity
Sonic Tool...................................................................................................................................................................................................... Por-1.....................................212
Sonic Tool...................................................................................................................................................................................................... Por-2.....................................213
Density Tool.................................................................................................................................................................................................. Por-3.....................................214
APS Near-to-Array (APLC) and Near-to-Far (FPLC) Logs............................................................................................................ Por-4.....................................216
Thermal Neutron Tool............................................................................................................................................................................... Por-5.....................................217
Thermal Neutron Tool—CNT-D and CNT-S 21⁄2-in. Tools.............................................................................................................. Por-6.....................................218
adnVISION475 4.75-in. Azimuthal Density Neutron Tool.............................................................................................................. Por-7.....................................219
adnVISION675 6.75-in. Azimuthal Density Neutron Tool.............................................................................................................. Por-8.....................................220
adnVISION825 8.25-in. Azimuthal Density Neutron Tool.............................................................................................................. Por-9.....................................221
EcoScope* 6.75-in. Integrated LWD Tool, BPHI Porosity.............................................................................................................. Por-10..................................222
EcoScope 6.75-in. Integrated LWD Tool, TNPH Porosity............................................................................................................... Por-10a................................223
CNL* Compensated Neutron Log and Litho-Density* Tool (fresh water in invaded zone)................................................ Por-11..................................225
CNL Compensated Neutron Log and Litho-Density Tool (salt water in invaded zone)....................................................... Por-12..................................226
APS and Litho-Density Tools................................................................................................................................................................... Por-13..................................227
APS and Litho-Density Tools (saltwater formation)....................................................................................................................... Por-14..................................228
adnVISION475 4.75-in. Azimuthal Density Neutron Tool.............................................................................................................. Por-15..................................229
adnVISION675 6.75-in. Azimuthal Density Neutron Tool.............................................................................................................. Por-16..................................230
adnVISION825 8.25-in. Azimuthal Density Neutron Tool.............................................................................................................. Por-17..................................231
EcoScope 6.75-in. Integrated LWD Tool.............................................................................................................................................. Por-18..................................232
EcoScope 6.75-in. Integrated LWD Tool ............................................................................................................................................. Por-19..................................233
Sonic and Thermal Neutron Crossplot................................................................................................................................................. Por-20..................................235
Sonic and Thermal Neutron Crossplot................................................................................................................................................. Por-21..................................236
Density and Sonic Crossplot.................................................................................................................................................................... Por-22..................................238
Density and Sonic Crossplot.................................................................................................................................................................... Por-23..................................239
Density and Neutron Tool........................................................................................................................................................................ Por-24..................................241
viii
Contents
Density and APS Epithermal Neutron Tool........................................................................................................................................ Por-25..................................243
Density, Neutron, and Rxo Logs.............................................................................................................................................................. Por-26..................................245
Hydrocarbon Density Estimation........................................................................................................................................................... Por-27..................................246
Saturation
Porosity Versus Formation Resistivity Factor.................................................................................................................................... SatOH-1...............................247
Spherical and Fracture Porosity............................................................................................................................................................ SatOH-2...............................248
Saturation Determination........................................................................................................................................................................ SatOH-3...............................250
Saturation Determination........................................................................................................................................................................ SatOH-4...............................252
Graphical Determination of Sw from Swt and Swb............................................................................................................................. SatOH-5...............................253
Porosity and Gas Saturation in Empty Hole....................................................................................................................................... SatOH-6...............................254
EPT Propagation Time.............................................................................................................................................................................. SatOH-7...............................255
EPT Attenuation.......................................................................................................................................................................................... SatOH-8...............................256
Capture Cross Section Tool..................................................................................................................................................................... SatCH-1...............................258
Capture Cross Section Tool..................................................................................................................................................................... SatCH-2...............................260
RSTPro* Reservoir Saturation Tool—1.6875 in. and 2.5 in..........................................................................................................................................................261
RSTPro Reservoir Saturation Tool—1.6875 in. and 2.5 in. in 6.125-in. Borehole.................................................................. SatCH-3...............................262
RSTPro Reservoir Saturation Tool—1.6875 in. and 2.5 in. in 9.875-in. Borehole.................................................................. SatCH-4...............................263
RSTPro Reservoir Saturation Tool—1.6875 in. and 2.5 in. in 8.125-in. Borehole with 4.5-in. Casing at 11.6 lbm/ft........ SatCH-5................................. 264
RSTPro Reservoir Saturation Tool—1.6875 in. and 2.5 in. in 7.875-in. Borehole with 5.5-in. Casing at 17 lbm/ft........... SatCH-6................................. 265
RSTPro Reservoir Saturation Tool—1.6875 in. and 2.5 in. in 8.5-in. Borehole with 7-in. Casing at 29 lbm/ft............. SatCH-7...............................266
RSTPro Reservoir Saturation Tool—1.6875 in. and 2.5 in. in 9.875-in. Borehole with 7-in. Casing at 29 lbm/ft......... SatCH-8...............................267
Permeability
Permeability from Porosity and Water Saturation........................................................................................................................... Perm-1..................................269
Permeability from Porosity and Water Saturation........................................................................................................................... Perm-2..................................270
Fluid Mobility Effect on Stoneley Slowness....................................................................................................................................... Perm-3..................................271
Cement Evaluation
Cement Bond Log—Casing Strength................................................................................................................................................... Cem-1....................................274
Appendixes
Appendix A
Linear Grid........................................................................................................................................................................................................................ 275
Log-Linear Grid................................................................................................................................................................................................................ 276
Water Saturation Grid for Resistivity Versus Porosity............................................................................................................................................. 277
Appendix B
Logging Tool Response in Sedimentary Minerals ..................................................................................................................................................... 279
Appendix C
Acoustic Characteristics of Common Formations and Fluids............................................................................................................................... 281
Appendix D
Conversions....................................................................................................................................................................................................................... 282
Appendix E
Symbols.............................................................................................................................................................................................................................. 285
Appendix F
Subscripts.......................................................................................................................................................................................................................... 287
Appendix G
Unit Abbreviations........................................................................................................................................................................................................... 290
Appendix H
References......................................................................................................................................................................................................................... 292
ix
Porosity
Foreword
Foreword
This edition of the Schlumberger “chartbook” presents several
innovations.
First, the charts were developed to achieve two purposes:
■ Correct raw measurements to account for environmental effects
Early downhole measurements were performed in rather uniform
conditions (vertical wells drilled through quasi-horizontal thick
beds, muds made of water with a narrow selection of additives,
and limited range of hole sizes), but today wells can be highly
deviated or horizontal, mud contents are diverse, and hole sizes
range from 2 to 40 in. Environmental effects may be large. In
addition, they compound. It is essential to correct for these effects
before the measurements are used.
■ Use environmentally corrected measurements for interpretation
Charts related to measurements that are no longer performed
are not included in this chartbook. However, because many oil and
gas companies use logs acquired years or even decades ago, the
second chartbook, Historical Log Interpretation Charts, contains
these old charts.
Why publish charts on paper in our electronic age? It is true that
software may be more effective than pencil to derive results. Even
more so, this chartbook cannot cope with the complex well situations
that are encountered. Using software is the only way to proceed.
Thus, the chartbook has two primary functions:
■ Training
The chartbook is essential for educating junior petrophysicists
about the different effects on the measurements. In the interpretation process, the chartbook unveils the relationships between
the different parameters.
■ Sensitivity analysis
A chart gives the user a graphical idea of the sensitivity of an output to the various inputs (see Chart Gen-1). The visual presentation is helpful for determining if an input parameter is critical.
The user can then focus on the most sensitive inputs.
xi
General
Symbols Used in Log Interpretation
Gen-1
(former Gen-3)
Gen
Resistivity of the zone
Resistivity of the water in the zone
Water saturation in the zone
Mud
Rm
Adjacent bed
Rs
hmc
Rmc
Flushed
zone
dh
(Bed
thickness)
Mudcake
Rx o
h
Uninvaded
zone
Rt
Zone of
transition
or
annulus
Rw
Ri
Sw
Rm f
Sx o
Rs
di
dj
Adjacent bed
(Invasion diameters)
∆rj
dh
Hole
diameter
© Schlumberger
Purpose
This diagram presents the symbols and their descriptions and relations as used in the charts. See Appendixes D and E for identification of the symbols.
Description
The wellbore is shown traversing adjacent beds above and below the
zone of interest. The symbols and descriptions provide a graphical
representation of the location of the various symbols within the wellbore and formations.
1
General
Estimation of Formation Temperature with Depth
Gen
Purpose
This chart has a twofold purpose. First, a geothermal gradient can
be assumed by entering the depth and a recorded temperature at
that depth. Second, for an assumed geothermal gradient, if the temp­
erature is known at one depth in the well, the temperature at
another depth in the well can be determined.
Description
Depth is on the y-axis and has the shallowest at the top and the
deepest at the bottom. Both feet and meters are used, on the left
and right axes, respectively. Temperature is plotted on the x-axis,
with Fahrenheit on the bottom and Celsius on the top of the chart.
The annual mean surface temperature is also presented in
Fahrenheit and Celsius.
2
Example
Given:
Find:
Answer:
Bottomhole depth = 11,000 ft and bottomhole temperature = 200°F (annual mean surface temperature = 80°F).
Temperature at 8,000 ft.
The intersection of 11,000 ft on the y-axis and 200°F
on the x-axis is a geothermal gradient of approximately
1.1°F/100 ft (Point A on the chart).
Move upward along an imaginary line parallel to the constructed gradient lines until the depth line for 8,000 ft is
intersected. This is Point B, for which the temperature
on the x-axis is approximately 167°F.
General
Estimation of Formation Temperature with Depth
Gen-2
(former Gen-6)
Gen
Temperature gradient conversions: 1°F/100 ft = 1.823°C/100 m
1°C/100 m = 0.5486°F/100 ft
Annual mean
surface temperature
27
16
Temperature (°C)
50
75
25
50
100
75
125
100
150
175
125
150
175
1
5
2
B
0.6
10
0.8
1.0
1.2
1.4 1.6°F/100 ft
Geothermal gradient
3
A
Depth
(thousands
of feet)
1.09
1.46
1.82
2.19
4
2.55 2.92°C/100 m
15
5
Depth
(thousands
of meters)
6
20
7
25
8
80
60
100
150
100
Annual mean
surface temperature
200
150
250
200
300
250
350
300
350
Temperature (°F)
© Schlumberger
3
General
Estimation of Rmf and Rmc
Gen-3
Fluid Properties
Gen
(former Gen-7)
Purpose
Direct measurements of filtrate and mudcake samples are preferred.
When these are not available, the mud filtrate resistivity (R mf) and
mudcake resistivity (R mc) can be estimated with the following
methods.
Mud Weight
Description
Method 1: Lowe and Dunlap
For freshwater muds with measured values of mud resistivity (R m)
between 0.1 and 2.0 ohm-m at 75°F [24°C] and measured values of
mud density (ρm) (also called mud weight) in pounds per gallon:
R
log  mf
 Rm

 = 0.396 − 0.0475 × ρm .

(
)
Method 2: Overton and Lipson
For drilling muds with measured values of R m between 0.1 and
10.0 ohm-m at 75°F [24°C] and the coefficient of mud (K m) given
as a function of mud weight from the table:
( )1.07
R mf = K m R m
2.65
R 
R mc = 0.69 R mf  m  .
 R mf 
( )
4
Example
Given:
Find:
Answer:
lbm/gal
kg/m3
Km
10
11
12
13
14
16
1,200
1,320
1,440
1,560
1,680
1,920
0.847
0.708
0.584
0.488
0.412
0.380
18
2,160
0.350
R m = 3.5 ohm-m at 75°F and mud weight = 12 lbm/gal
[1,440 kg/m3].
Estimated values of Rmf and Rmc.
From the table, Km = 0.584.
R mf = (0.584)(3.5)1.07 = 2.23 ohm-m at 75°F.
R mc = 0.69(2.23)(3.5/2.23)2.65 = 5.07 ohm-m at 75°F.
General
Equivalent NaCl Salinity of Salts
Gen-4
(former Gen-8)
Gen
2.0
Li (2.5)†
OH (5.5)†
2.0
NH4 (1.9)†
Mg
1.5
K
Ca
1.0
CO3
Na and CI (1.0)
1.0
K
Multiplier
SO4
0.5
NO3 (0.55)†
Br (0.44)†
Ca
CO3
HCO3
SO4
I (0.28)
†
HCO3
0
0
Mg
–0.5
10
20
50
100
200
500
1,000 2,000
5,000 10,000 20,000
50,000 100,000
300,000
Total solids concentration (ppm or mg/kg)
† Multipliers that do not vary appreciably for low concentrations
(less than about 10,000 ppm) are shown at the left margin of the chart
© Schlumberger
Purpose
This chart is used to approximate the parts-per-million (ppm) concentration of a sodium chloride (NaCl) solution for which the total
solids concentration of the solution is known. Once the equivalent
concentration of the solution is known, the resistivity of the solution
for a given temperature can be estimated with Chart Gen-6.
Description
The x-axis of the semilog chart is scaled in total solids concentration
and the y-axis is the weighting multiplier. The curve set represents
the various multipliers for the solids typically in formation water.
Example
Given:
Find:
Answer:
Formation water sample with solids concentrations
of calcium (Ca) = 460 ppm, sulfate (SO4) = 1,400 ppm,
and Na plus Cl = 19,000 ppm. Total solids concentration
= 460 + 1,400 + 19,000 = 20,860 ppm.
Equivalent NaCl solution in ppm.
Enter the x-axis at 20,860 ppm and read the multiplier
value for each of the solids curves from the y-axis:
Ca = 0.81, SO4 = 0.45, and NaCl = 1.0. Multiply each
concentration by its multiplier:
(460 × 0.81) + (1,400 × 0.45) + (19,000 × 1.0) = 20,000 ppm.
5
General
Concentration of NaCl Solutions
Gen-5
Gen
Concentrations of NaCl Solutions
g/L at
77°F
ppm
0.15
150
0.2
0.3
300
0.4
400
0.5
0.6
500
600
0.8
800
1.0
1,000
1.5
1,500
2
2,000
3
3,000
4
4,000
5
6
5,000
6,000
8
8,000
10
10,000
15
15,000
20
20,000
30
30,000
40
40,000
50
60
80
100
125
150
200
250
300
© Schlumberger
6
200
60,000
80,000
100,000
150,000
200,000
250,000
grains/gal
at 77°F
10
Density of NaCl
solution at
77°F [25°C]
1.00
12.5
15
3.5
90
80
70
60
2.5
40
30
1.2
1.1
20
2.0
10
1.0
1.01
2,000
1.02
2,500
3,000
1.03
1.04
1.05
1.06
1.07
1.08
1.09
1.10
1.12
1.14
1.16
1.18
1.20
0
0.9
0.8
0.64
0.66
0.68
0.70
0.74
0.76
50
1.3
1.005
0.62
0.72
1.5
200
5,000
6,000
7,000
8,000
9,000
10,000
12,500
15,000
17,500
100
1.6
1.4
Specific
gravity (sg) at 60°F
0.60
2.0
3.0
50
60
70
80
90
100
125
150
4,000
°API
1.7
40
500
600
700
800
900
1,000
1,250
1,500
°C/100 m
Oil Gravity
1.8
25
30
400
°F/100 ft
1.9
20
250
300
Temperature Gradient
Conversion
1.5
0.7
0.6
1.0
1°F/100 ft = 1.822°C/100 m
1°C/100 m = 0.5488°F/100 ft
°API =
0.78
0.80
0.82
0.84
0.86
0.88
0.90
0.92
0.94
0.96
0.98
1.00
1.02
1.04
1.06
1.08
141.5
− 131.5
sg at 60°F
General
Resistivity of NaCl Water Solutions
Purpose
This chart has a twofold purpose. The first is to determine the resistivity of an equivalent NaCl concentration (from Chart Gen-4) at a
specific temperature. The second is to provide a transition of resis­
tivity at a specific temperature to another temperature. The solution
resistivity value and temperature at which the value was determined
are used to approximate the NaCl ppm concentration.
Description
The two-cycle log scale on the x-axis presents two temperature
scales for Fahrenheit and Celsius. Resistivity values are on the left
four-cycle log scale y-axis. The NaCl concentration in ppm and
grains/gal at 75°F [24°C] is on the right y-axis. The conversion
approximation equation for the temperature (T) effect on the
resistivity (R) value at the top of the chart is valid only for the
temperature range of 68° to 212°F [20° to 100°C].
Example Two
Given:
Solution resistivity = 0.3 ohm-m at 75°F.
Find:
Solution resistivity at 200°F [93°C].
Answer 1: Enter 0.3 ohm-m and 75°F and find their intersection
on the 20,000-ppm concentration line. Follow the line to
the right to intersect the 200°F vertical line (interpolate
between existing lines if necessary). The resistivity value
for this point on the left y-axis is 0.115 ohm-m.
Answer 2: Resistivity at 200°F = resistivity at 75°F × [(75 + 6.77)/
(200 + 6.77)] = 0.3 × (81.77/206.77) = 0.1186 ohm-m.
Example One
Given:
NaCl equivalent concentration = 20,000 ppm.
Temperature of concentration = 75°F.
Find:
Resistivity of the solution.
Answer:
Enter the ppm concentration on the y-axis and the tem­
perature on the x-axis to locate their point of intersection on the chart. The value of this point on the left
y-axis is 0.3 ohm-m at 75°F.
continued on next page
7
Gen
General
Resistivity of NaCl Water Solutions
Gen-6
(former Gen-9)
Gen
Conversion approximated by R2 = R1 [(T1 + 6.77)/(T2 + 6.77)]°F or R2 = R1 [(T1 + 21.5)/(T2 + 21.5)]°C
10
8
NaCl
concentration
6
(ppm)
5
4
200
10
300
15
400
20
25
30
0.4
500
600
700
800
1,00
0
1,20
0
1,40
0
1,70
0
2,00
0
0.3
3,00
0
150
4,00
0
5,00
0
6,00
0
7,00
0
8,00
0
10,0
00
12,0
00
14,0
00
17,0
00
20,0
00
200
30,00
0
1,500
40,0
00
50,0
00
60,0
0
70,000
80,000
0
100,0
00
120,0
140,0 00
00
170,0
200,000
00
250,0
00
2,000
2,500
3,000
3
2
1
0.8
0.6
0.5
Resistivity
of solution
(ohm-m)
0.2
0.1
0.08
0.06
0.05
0.04
0.03
0.02
280,000 ppm
0.01
° F 50
°C 10
300,000 ppm
20
75
30
100
40
125
150
200
50 60 70 80 90 100
Temperature
© Schlumberger
8
(grains/gal
at 75°F)
250
300 350 400
120 140 160 180 200
40
50
100
250
300
400
500
1,000
4,000
5,000
10,000
15,000
20,000
General
Density of Water and Hydrogen Index of Water and Hydrocarbons
Gen-7
Gen
Water
Temperature (°C)
1.20
1.15
1.10
25 50
250
,000
200
,000
150,0
150
Hydrogen Index of Salt Water
200
1.05
ppm
ppm
1.00
00 p
pm
100,00
Water
density
(g/cm3)
100
0 pp
1.05
50,000
m
Hydrogen
index
ppm
1.00
Dis
tille
0.95
dw
0.95
ate
r
0.90
0.90
0.85
40 100
Pressure
200
300
0.85
400 440
Temperature (°F)
7,000 psi NaCl
1,000 psi
14.7 psi
0
50
100
150
200
250
Salinity (kppm or g/kg)
Hydrocarbons
Hydrogen Index of Live Hydrocarbons and Gas
1.2
1.0
0.8
Hydrogen
index
0.6
0.4
0.2
0
© Schlumberger
0
1.0
0.8
0.4
0.6
0.2
Hydrocarbon density (g/cm3)
Purpose
These charts are for determination of the density (g/cm3) and hydrogen index of water for known values of temperature, pressure, and
salinity of the water. From a known hydrocarbon density of oil, a
determination of the hydrogen index of the oil can be obtained.
Description: Density of Water
To obtain the density of the water, enter the desired temperature (°F
at the bottom x-axis or °C at the top) and intersect the pressure and
salinity in the chart. From that point read the density on the y-axis.
1.2
Example: Density of Water
Given:
Temperature = 200°F [93°C], pressure = 7,000 psi, and
salinity = 250,000 ppm.
Answer:
Density of water = 1.15 g/cm3.
Example: Hydrogen Index of Salt Water
Given:
Salinity of saltwater = 125,000 ppm.
Answer:
Hydrogen index = 0.95.
Example: Hydrogen Index of Hydrocarbons
Given:
Oil density = 0.60 g/cm3.
Answer:
Hydrocarbon index = approximately 0.91.
9
General
Density and Hydrogen Index of Natural Gas
Gen
Hgas
Gas gravity = 0.6
(Air = 1.0)
0.3
Gas
density
(g/cm3)
Gen-8
0.7
100
0.6
150
200
250
300
350
0.2
0.5
0.4
Gas
temperature
(°F)
0.3
0.1
0.2
0.1
0
0
0
4
2
8
6
10
Gas pressure × 1,000 (psia)
0.5
Gas gravity = 0.65
0.4
Pressure (psi)
17,500
15,000
12,500
10,000
0.3
Gas
density
(g/cm3)
7,500
0.2
5,000
0.1
2,500
0
14.7
100
© Schlumberger
Purpose
This chart can be used to determine more than one characteristic
of natural gas under different conditions. The characteristics are
gas density (ρg), gas pressure, and hydrogen index (Hgas).
Description
For known values of gas density, pressure, and temperature, the value
of Hgas can be determined. If only the gas pressure and temperature
are known, then the gas density and Hgas can be determined. If the
gas density and temperature are known, then the gas pressure and
Hgas can be determined.
10
300
200
400
Temperature (°F)
Example
Given:
Find:
Answer:
Gas density = 0.2 g/cm3 and temperature = 200°F.
Gas pressure and hydrogen index.
Gas pressure = approximately 5,200 psi and Hgas = 0.44.
General
Sound Velocity of Hydrocarbons
Gen-9
Gen
Natural Gas
Temperature (C)
5,000
0
50
100
150
200
200
Gas gravity = 0.65
Pressure (psi)
4,000
250
17,500
Sound
velocity
(ft/s)
300
15,000
3,000
12,500
400
10,000
2,000
500
7,500
14.7
5,000
1,000
Sound
slowness
(µs/ft)
1,000
2,500
2,000
0
50
100
150
200
250
300
350
Temperature (F)
© Schlumberger
Purpose
This chart is used to determine the sound velocity (ft/s) and sound
slowness (μs/ft) of gas in the formation. These values are helpful in
sonic and seismic interpretations.
Description
Enter the chart with the temperature (Celsius along the top x-axis
and Fahrenheit along the bottom) to intersect the formation
pore pressure.
11
General
Gas Effect on Compressional Slowness
Gen-9a
Gen
Sandstone
200
∆tc
(µs/ft)
200 µs/ft
Wet
sand
110 µs/ft
100
90 µs/ft
70 µs/ft
50
0
20
40
60
80
100
Liquid saturation (%)
Wood’s law (e = 5)
Power law (e = 3)
© Schlumberger
Purpose
This chart illustrates the effect that gas in the formation has on the
slowness time of sound from the sonic tool to anticipate the slowness
of a formation that contains gas and liquid.
12
Description
Enter the chart with the compressional slowness time (Δtc) from the
sonic log on the y-axis and the liquid saturation of the formation on
the x-axis. The curves are used to determine the gas effect on the
basis of which correlation (Wood’s law or Power law) is applied. The
slowing effect begins sooner for the Power law correlation. The
Wood’s law correlation slightly increases Δtc values as the formation
liquid saturation increases whereas the Power law correlation
decreases Δtc values from about 20% liquid saturation.
General
Gas Effect on Acoustic Velocity
Gen-9b
Sandstone and Limestone
Gen
Sandstone
25
No gas
Gas bearing
20
Velocity
(1,000 × ft/s)
15
Vp
10
Vs
5
0
0
10
30
20
40
Porosity (p.u.)
Limestone
25
No gas
Gas bearing
20
15
Vp
Velocity
(1,000 × ft/s)
10
Vs
5
0
0
10
20
30
40
Porosity (p.u.)
© Schlumberger
Purpose
This chart is used to determine porosity from the compressional
wave or shear wave velocity (Vp and Vs, respectively).
Description
Enter Vp or Vs on the y-axis to intersect the appropriate curve. Read
the porosity for the sandstone or limestone formation on the x-axis.
13
General
Nuclear Magnetic Resonance Relaxation Times of Water
Gen-10
Gen
Transverse (Bulk and Diffusion)
Relaxation Time of Water
Longitudinal (Bulk) Relaxation
Time of Water
100
100
T1
10
Relaxation
time (s)
Relaxation
time (s)
1.0
0.1
10
T2 (TE = 0.2 ms)
1.0
T2 (TE = 0.32 ms)
0.1
T2 (TE = 1 ms)
T2 (TE = 2 ms)
0.01
20
60
100
140
180
Temperature (C)
0.01
20
60
100
140
180
Temperature (C)
© Schlumberger
Purpose
Longitudinal (Bulk) Relaxation Time of Pure Water
This chart provides an approximation of the bulk relaxation time
(T1) of pure water depending on the temperature of the water.
Transverse (Bulk and Diffusion) Relaxation Time of Water
in the Formation
Determining the bulk and diffusion relaxation time (T2) from this
chart requires knowledge of both the formation temperature and
the echo spacing (TE) used to acquire the data. These data are presented graphically on the log and are the basis of the water or
hydrocarbon interpretation of the zone of interest.
14
Description
Longitudinal Relaxation Time
The chart relation is for pure water—the additives in drilling fluids
reduce the relaxation time (T1) of water in the invaded zone. The
two major contributors to the reduction are surfactants added to the
drilling fluid and the molecular interactions of the mud filtrate contained in the pore spaces and matrix minerals of the formation.
Transverse Relaxation Time
The relaxation time (T2) determination is based on the formation
temperature and echo spacing used to acquire the measurement.
The TE value is listed in the parameter section of the log. Using
the T2 measurement from a known water sand or based on local
experience further aids in determining whether a zone of
interest contains hydrocarbons, water, or both.
General
Nuclear Magnetic Resonance Relaxation Times of Hydrocarbons
10
Light oil: 45°–60° API
0.65–0.75 g/cm3
1
Medium oil: 25°–40° API
0.75–0.85 g/cm3
0.1
T1
0.01
T2 (s)
0.01
Heavy oil: 10°–20° API
0.85–0.95 g/cm3
0.001
0.0001
0.1
10
1
100
0.001
1,000
10,000 100,000
0.0001
0.1
10
1
Viscosity (cp)
Hydrocarbon Diffusion Coefficient
10–3
Gen
TE = 0.2 ms
TE = 0.32 ms
TE = 1 ms
TE = 2 ms
1
0.1
T1 (s)
Transverse (Bulk and Diffusion) Relaxation
Time of Crude Oil
Longitudinal (Bulk) Relaxation
Time of Crude Oil
10
Gen-11a
100
1,000
Viscosity (cp)
10,000 100,000
Water Diffusion Coefficient
20
15
10–4
Oil (9° at 20°C)
Diffusion
(cm2/s)
Diffusion
(10 –5 cm2/s)
10–5
10
Oil (40° at 20°C)
10–6
10–7
© Schlumberger
5
0
50
100
150
200
Temperature (°C)
Purpose
Longitudinal (Bulk) Relaxation Time of Crude Oil
This chart is used to predict the T1 of crude oils with various viscosities and densities or specific gravities to assist in interpretation of
the fluid content of the formation of interest.
Transverse (Bulk and Diffusion) Relaxation Time
Known values of T2 and TE can be used to approximate the viscosity
by using this chart.
Diffusion Coefficients for Hydrocarbon and Water
These charts are used to predict the diffusion coefficient of hydro­
carbon as a function of formation temperature and viscosity and
of water as a function of formation temperature.
0
0
50
100
150
200
Temperature (°C)
Description
Longitudinal (Bulk) Relaxation Time
This chart is divided into three distinct sections based on the composition of the oil measured. The type of oil contained in the formation
can be determined from the measured T1 and viscosity determined
from the transverse relaxation time chart.
Transverse (Bulk and Diffusion) Relaxation Time
The viscosity can be determined with values of the measured T2 and
TE for input to the longitudinal relaxation time chart to identify the
type of oil in the formation.
15
General
Nuclear Magnetic Resonance Relaxation Times of Hydrocarbons
Gen
Methane Diffusion Coefficient
35
Longitudinal (Bulk) Relaxation
Time of Methane
10
25°C
75°C
125°C
175°C
30
6
3,000
20
Diffusion
(10–4 cm2/s)
8
1,600 psi
25
Gen-11b
3,900
15
4,500
10
8,300
T1 (s)
2
15,500
5
4
22,800
0
0
50
100
150
0
200
0
3,000
Temperature (°C)
100
T2 (s)
0.1
Transverse (Bulk and Diffusion)
Relaxation Time of Methane
Hydrogen Index of Live Hydrocarbons and Gas
1.2
1.0
0.8
TE = 0.2 ms
Hydrogen
index
TE = 0.32 ms
0.6
0.4
TE = 1 ms
0.01
0.2
TE = 2 ms
0.001
10–4
12,000
Pressure (psi)
10
1
9,000
6,000
0
10–2
10–3
Diffusion (cm /s)
2
0
0.2
0.4
0.6
0.8
1.0
1.2
Hydrocarbon density (g/cm )
3
© Schlumberger
Purpose
Methane Diffusion Coefficient
This chart is used to determine the diffusion coefficient of methane
at a known formation temperature and pressure.
Longitudinal and Transverse Relaxation Times of Methane
These charts are used to determine the longitudinal relaxation time
(T1) of methane by using the formation temperature and pressure
(see Reference 48) and the transverse relaxation time (T2) of
methane by using the diffusion and echo spacing (TE), respectively.
16
Hydrogen Index of Live Hydrocarbons and Gas
This chart is used to determine the hydrogen index from the hydrocarbon density.
General
Capture Cross Section of NaCl Water Solutions
Purpose
The sigma value (Σw) of a saltwater solution can be determined from
this chart. The sigma water value is used to calculate the water saturation of a formation.
Description
Charts Gen-12 and Gen-13 define sigma water for pressure conditions of ambient through 20,000 psi [138 MPa] and temperatures
from 68° to 500°F [20° to 260°C]. Enter the appropriate chart for
the pressure value with the known water salinity on the y-axis and
move horizontally to intersect the formation temperature. The sigma
of the formation water for the intersection point is on the x-axis.
Example
Given:
Water salinity = 125,000 ppm, temperature = 68°F at
ambient pressure, and formation temperature = 190°F
at 5,000 psi.
Find:
Σw at ambient conditions and Σw of the formation.
Answer:
Σw = 69 c.u. and Σw of the formation = 67 c.u.
If the sigma water apparent (Σwa) is known from a clean water
sand, then the salinity of the formation can be determined by entering the chart from the sigma water value on the x-axis to intersect
the pressure and temperature values.
continued on next page
17
Gen
General
Capture Cross Section of NaCl Water Solutions
Gen-12
(former Tcor-2a)
Gen
300
300
]
°C
93 ]
F [ 0°C
°
0 2
20 °F [
68
275
250
250
225
200
200
Am
bi
en
t
225
175
150
C]
5° ]
20 0°C
F [ [15 °C]
°
3 ]
0
40 00°F F [9 0°C
3 00° [2
2 8°F
6
125
1,0
00
ps
i[
6.9
M
Pa
]
100
75
50
25
Equivalent water salinity
(1,000 × ppm NaCl)
275
175
0
150
125
125
100
25
250
225
200
C]
5° ]
20 0°C
F [ [15 °C]
°
3 ]
0
40 00°F F [9 0°C
3 00° [2
2 8°F
6
300
275
250
225
5,0
00
ps
i[
34
M
Pa
]
50
275
175
150
75
300
200
175
150
0
125
100
100
75
75
50
50
25
25
0
© Schlumberger
18
0
10
20
30
40
50
60
70
80
90
100 110 120
130
0
140
General
Capture Cross Section of NaCl Water Solutions
Gen-13
(former Tcor-2b)
300
300
C]
5° ]
20 0°C
F [ [15 °C]
°
3 ]
0
40 00°F F [9 0°C
3 00° [2
2 8°F
6
275
250
225
275
250
10
,00
0p
si
[6
9M
Pa
]
225
200
175
150
200
300
C]
5° C]
[20 50° C]
F
0° [1 3° ]
40 00°F F [9 0°C
3 00° [2
2 8°F
6
125
15
,00
0p
si
[1
03
M
Pa
]
100
75
50
25
Equivalent water salinity
(1,000 × ppm NaCl)
Gen
175
0
150
125
125
100
225
200
300
C]
0° C]
[26 05° °C]
F
0° [2 50 ]
50 00°F F [1 93°C ]
4 00° F [ 0°C
3 00° [2
2 8°F
6
20
,00
0p
si
[1
38
M
Pa
]
50
25
250
175
150
75
275
0
275
250
225
200
175
150
125
100
100
75
75
50
50
25
25
0
0
10
20
30
40
50
60
70
80
90
100 110 120 130
0
140
© Schlumberger
Purpose
Chart Gen-13 continues Chart Gen-12 at higher pressure values for
the determination of Σw of a saltwater solution.
19
General
Capture Cross Section of Hydrocarbons
Gen
Purpose
Sigma hydrocarbon (Σh) for gas or oil can be determined by using
this chart. Sigma hydrocarbon is used to calculate the water saturation of a formation.
Example
Given:
Description
One set of charts is for measurement in metric units and the other
is for measurements in “customary” oilfield units.
For gas, enter the background chart of a chart set with the reservoir pressure and temperature. At that intersection point move left
to the y-axis and read the sigma of methane gas.
For oil, use the foreground chart and enter the solution gas/oil
ratio (GOR) of the oil on the x-axis. Move upward to intersect the
appropriate API gravity curve for the oil. From this intersection
point, move horizontally left and read the sigma of the oil on
the y-axis.
Find:
Answer:
20
Reservoir pressure = 8,000 psi, reservoir temperature =
300°F, gravity of reservoir oil = 30°API, and solution
GOR = 200.
Sigma gas and sigma oil.
Sigma gas = 10 c.u. and sigma oil = 21.6 c.u.
0.74 or 0.94 mg/m3
Σh (c.u.)
2.5
18
General
Co
nd
en
sa
te
0
16
Capture Cross Section of Hydrocarbons
2
10
100
1,000
Gen-14
(former Tcor-1)
2,000
Solution GOR (m3/m3)
Gen
Reservoir pressure (psia)
20.0 0
4,000
8,000
12,000
16,000
Methane
17.5
68
125
15.0
Customary
200
300
400
500
12.5
Σh (c.u.)
20,000
10.0
Temperature (°F)
7.5
Liquid hydrocarbons
22
5.0
30°, 40°, and 50°API
20
20° and 60°API
Σh (c.u.)
2.5
Co
nd
en
sa
te
18
0
16
10
100
1,000
10,000
Solution GOR (ft /bbl)
3
Reservoir pressure (mPa)
20.0
0
14
28
41
55
69
83
97
124
138
Methane
17.5
20
52
15.0
93
Metric
150
205
260
12.5
Σh (c.u.)
110
10.0
Temperature (°C)
7.5
Liquid hydrocarbons
22
0.78 to 0.88 mg/m3
5.0
20
0.74 or 0.94 mg/m3
Σh (c.u.)
2.5
18
Co
nd
en
sa
te
0
16
2
10
100
1,000
2,000
Solution GOR (m /m )
3
© Schlumberger
21
Reservoir pressure (psia)
0
4,000
8,000
12,000
3
16,000
20,000
General
EPT* Propagation Time of NaCl Water Solutions
Gen-15
(former EPTcor-1)
Gen
90
120°C
250°F
80
100°C
200°F
80°C
175°F
70
150°F
60°C
125°F
60
40°C
100°F
tpw (ns/m)
50
75°F
20°C
40
30
20
0
50
100
150
200
250
Equivalent water salinity (1,000 × ppm or g/kg NaCl)
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is designed to determine the propagation time (tpw) of
saltwater solutions. The value of t pw of a water zone is used to determine the temperature variation of the salinity of the formation water.
22
Description
Enter the chart with the known salinity of the zone of interest and
move upward to the formation temperature curve. From that intersection point move horizontally left and read the propagation time
of the water in the formation on the y-axis. Conversely, enter the
chart with a known value of tpw from the EPT Electromagnetic
Propagation Tool log to intersect the formation temperature curve
and read the water salinity at the bottom of the chart.
General
EPT* Attenuation of NaCl Water Solutions
Gen-16
(former EPTcor-2)
Gen
5,000
120°C
250°F
100°C
200°F
80°C
175°F
150°F
60°C
125°F
40°C
100°F
4,000
Attenuation,
Aw
(dB/m)
3,000
75°F
20°C
2,000
1,000
0
0
50
100
150
200
250
Equivalent water salinity (kppm or g/kg NaCl)
EPT-D Spreading Loss
–40
–60
–80
–100
–120
–140
Correction
to EATT
(dB/m)
–160
–180
–200
0
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is designed to estimate the attenuation of saltwater solutions. The attenuation (Aw) value of a water zone is used in conjunction with the spreading loss determined from the EPT propagation
time measurement (tpl) to determine the saturation of the flushed
zone by using Chart SatOH-8.
5
10
15
20
25
30
Uncorrected t pl (ns/m)
Description
Enter the chart with the known salinity of the zone of interest and
move upward to the formation temperature curve. From that intersection point move horizontally left and read the attenuation of the water
in the formation on the y-axis. Conversely, enter the chart with a known
EATT attenuation value of Aw from the EPT Electromagnetic
Propagation Tool log to intersect the formation temperature curve
and read the water salinity at the bottom of the chart.
23
General
EPT* Propagation Time–Attenuation Crossplot
Gen-16a
Sandstone Formation at 150°F [60°C]
Gen
1,000
Rmfa from EPT log (ohm-m)
900
0.02
0.05
0.1
Sandstone at 150°F [60°C]
800
700
0.2
600
Attenuation
(dB/m)
500
sity
(φ
EP
T)
400
E PT
200
1.0
100
0
0.5
por
o
300
10
7
8
9
10
11
12
13
14
15
2.0
50
40
30
20
16
17
5.0
10.0
50.0
18
19
20
21
22
23
24
25
tpl (ns/m)
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to determine the apparent resistivity of the mud
filtrate (Rmfa) from measurements from the EPT Electromagnetic
Propagation Tool. The porosity of the formation (ϕEPT) can also be
estimated. Porosity and mud filtrate resistivity values are used in
determining the water saturation.
Description
Enter the chart with the known attenuation and propagation time
(tpl). The intersection of those values identifies Rmfa and ϕEPT from
the two sets of curves. This chart is characterized for a sandstone
formation at a temperature of 150°F [60°C].
24
Example
Given:
Find:
Answer:
Attenuation = 300 dB/m and tpl = 13 ns/m.
Apparent resistivity of the mud filtrate and EPT porosity.
Rmfa = 0.1 ohm-m and ϕEPT = 20 p.u.
Gamma Ray—Wireline
Scintillation Gamma Ray—33⁄8- and 111⁄16-in. Tools
GR–1
Gamma Ray Correction for Hole Size and Mud Weight
(former GR-1)
Scintillation Gamma Ray
10.0
GR
7.0
5.0
3 3⁄8-in. tool, centered
3.0
111⁄16-in. tool, centered
Correction
factor
2.0
3 3⁄8-in. tool, eccentered
111⁄16-in. tool, eccentered
1.0
0.7
0.5
0.3
0
5
10
15
20
25
30
35
40
t (g/cm2)
© Schlumberger
Purpose
This chart provides a correction factor for measured values of formation gamma ray (GR) in gAPI units. If the mud contains barite, the
additional correction of Chart GR-2 should also be made.
CF′m is the correction factor for centered tools, while CF′o is the correction factor for eccentered tools. Both are corrected for barite if
it is present in the borehole. S is the actual standoff, and Sm is the
standoff with the tool centered.
Description
The semilog chart has the t factor on the x-axis and the correction
factor on the y-axis.
The input parameter, t, in g/cm2, is calculated as follows:
Example
Given:
t=
( )
(
2.54 d sonde
Wmud  2.54 d h
−

8.345 
2
2
)  ,

Find:
Answer:
GR = 36 API units (gAPI), dh = 12 in., mud weight =
12 lbm/gal, tool OD = 33⁄8 in., and the tool is centered.
Corrected GR value.
t=
where
Wmud = mud weight (lbm/gal)
dh = diameter of wellbore (in.)
dsonde = outside diameter (OD) of tool (in.).
( )
(
2.54 3.375
12  2.54 12
−

8.345 
2
2
) = 15.88 g /cm2.

Enter the chart at 15.8 on the x-axis and move upward to
intersect the 33⁄8-in. centered curve. The corresponding
correction factor is 1.6.
The correction for standoff is
2
 S − Sm 
CF ′ = CFm′ + ( CFo′ − CFm′ ) 
.
 S 
1.6 × 36 gAPI = 58 gAPI.
m
25
Gamma Ray—Wireline
Scintillation Gamma Ray—33⁄8- and 111⁄16-in. Tools
GR-2
Additional Gamma Ray Correction for Barite Mud in Various-Size Boreholes
(former GR-2)
1.2
1.0
111⁄16-in. tool, centered
GR
0.8
Bmud
0.6
111⁄16-in. tool, eccentered
0.4
33⁄8-in. tool, centered
0.2
0
33⁄8-in. tool, eccentered
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Mud weight (lbm/gal)
1.2
1.0
0.8
Fbh
33⁄8-in. tool
0.6
111⁄16-in. tool
0.4
0.2
0
0
1
2
3
4
5
6
7
8
9
10
dh – dsonde (in.)
© Schlumberger
Purpose
Once the GR reading has been corrected with Chart GR-1, these
charts are an additional correction to be applied if the mud contains
barite.
Description
Two components needed to complete correction of the GR reading
are determined with these charts: barite mud factor (Bmud) and
borehole function factor (Fbh).
Example
Given:
Find:
Answer:
26
Borehole diameter = 6.0 in., tool OD = 33⁄8 in., the tool
is centered, mud weight = 12 lbm/gal, measured
GR = 36 gAPI.
Corrected GR value.
Enter the upper chart for Bmud versus mud weight at
12 lbm/gal on the x-axis. The intersection point with the
33⁄8-in. centered curve is Bmud < 0.15 on the y-axis.
Determine (dh – dsonde) as 6 – 3.375 = 2.625 in. and enter
that value on the lower chart for Fbh versus
(dh – dsonde) on the x-axis. Move upward to intersect
the 3 3⁄8-in. curve, at which Fbh = 0.81.
Determine the new value of t using the equation from
Chart GR-1:
t=
=
(
( )
2.54 d sonde
Wmud  2.54 d h
−


8.345 
2
2
()
(
12  2.54 6 2.54 3.375
−

8.345  2
2
) 

)  = 4.8 g /cm2.

The correction factor determined from Chart GR-1 is 0.95.
The complete correction factor is
(Chart GR-1 correction factor) × [1 + (Bmud × Fbh)]
= 1.12 × [1 + (0.15 × 0.81)] = 1.26.
Corrected GR = 36 × 1.26 = 45.4 gAPI.
Gamma Ray—Wireline
Scintillation Gamma Ray—33⁄8- and 111⁄16-in. Tools
GR-3
Borehole Correction for Cased Hole
(former GR-3)
Scintillation Gamma Ray
10.0
GR
7.0
5.0
33⁄8-in. tool
3.0
111⁄16-in. tool
Correction
factor
2.0
1.0
0.7
0.5
0.3
0
5
10
15
20
25
30
35
40
t (g/cm2)
© Schlumberger
Purpose
This chart is used to compensate for the effects of the casing,
cement sheath, and borehole fluid on the GR count rate in cased
holes for conditions of an eccentered 33⁄8-in. tool in an 8-in. borehole
with 10-lbm/gal mud.
Description
In small boreholes the count rate can be too large, and in larger
boreholes the count rate can be too small. The chart is based on
openhole Chart GR-1, modified by laboratory and Monte Carlo
calculations to provide a correction factor for application to
the measured GR count rate in cased hole environments:
t=
(
)
(
)
(
Example
Given:
Find:
Answer:
)

2.54  Wm
d
− d sonde + ρcsg d ODcsg − d IDcsg + ρcement d h − d ODcsg  .

2  8.345 IDcsg

GR = 19 gAPI, hole diameter (dh) = 12 in., casing OD
(dODcsg) = 95⁄8 in. and 43.5 lbm/ft, casing ID (dIDcsg) =
8.755 in., casing density (ρcsg) = 7.96 g/cm3, tool OD
(dsonde) = 33⁄8 in., cement density (ρcement) = 2.0 g/cm3,
and mud weight (Wm) = 8.345 lbm/gal.
Corrected cased hole GR value.
The chart input factor calculated with the equation is
t = 21.7 g/cm2. Enter the chart at 21.7 on the x-axis. At
the intersection point with the 33⁄8-in. curve, the value of
the correction factor on the y-axis is 2.0. The GR value is
corrected by multiplying by the correction factor:
19 gAPI × 2.0 = 38 gAPI.
27
Gamma Ray—LWD
SlimPulse* and E-Pulse* Gamma Ray Tools
GR-6
Borehole Correction for Open Hole
11
GR
10
9
17.5-in. bit
8
13.5-in. bit
7
Correction
factor
6
12.25-in. bit
5
4
9.875-in. bit
8.5-in. bit
3
2
7-in. bit
6-in. bit
1
0
8
9
10
11
12
13
14
15
16
17
18
19
Mud weight (lbm/gal)
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to provide a correction factor for gamma ray
values measured with the SlimPulse third-generation slim measurements-while-drilling (MWD) tool or the E-Pulse electromagnetic
telemetry tool. These environmental corrections for mud weight
and bit size are already applied to the gamma ray presented on
the logs.
28
Description
Enter the chart with the mud weight on the x-axis and move
upward to intersect the appropriate openhole size. Interpolate
between lines as necessary. At the intersection point, move
horizontally left to the y-axis to read the correction factor that
the SlimPulse or E-Pulse gamma ray value was multiplied­by to
obtain the corrected gamma ray value in gAPI units.
Gamma Ray—LWD
ImPulse* Gamma Ray— 4.75-in. Tool
GR-7
Borehole Correction for Open Hole
1.75
GR
1.50
8.5-in. bit
Correction
factor
1.25
7-in. bit
6-in. bit
1.00
0.75
8
9
10
11
12
13
14
15
16
17
18
19
Mud weight (lbm/gal)
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to provide a correction factor for gamma ray
values measured with the ImPulse integrated MWD platform. These
environ­mental corrections for mud weight and bit size are already
applied to the gamma ray presented on the logs.
Description
Enter the chart with the mud weight on the x-axis and move
upward to intersect the appropriate bit size. Interpolate between
lines as necessary. At the intersection point, move horizontally left
to the y-axis to read the correction factor that the ImPulse gamma
ray value was multiplied by to obtain the corrected gamma ray
value in gAPI units.
29
Gamma Ray—LWD
PowerPulse* and TeleScope* Gamma Ray—6.75-in. Tools
GR-9
Borehole Correction for Open Hole
PowerPulse and TeleScope Gamma Ray
GR
3.00
2.75
2.50
2.25
Correction
factor
12.25-in. bit
2.00
10.625-in. bit
9.875-in. bit
1.75
8.75-in. bit
8.5-in. bit
1.50
1.25
1.00
8
9
10
11
12
13
14
15
16
17
18
19
Mud weight (lbm/gal)
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to provide a correction factor for gamma ray values
measured with the PowerPulse 6.75-in. MWD telemetry system and
TeleScope 6.75-in. high-speed telemetry-while-drilling service.
These environmental corrections for mud weight and bit size are
already applied to the gamma ray presented on the logs.
30
Description
Enter the chart with the mud weight on the x-axis and move upward
to intersect the appropriate bit size. Interpolate between lines as
necessary. At the intersection point, move hori­zontally left to the
y-axis to read the correction factor that the PowerPulse or
TeleScope gamma ray value was multiplied by to obtain the corrected gamma ray value in gAPI units.
Gamma Ray—LWD
PowerPulse* Gamma Ray—8.25-in. Normal-Flow Tool
GR-10
Borehole Correction for Open Hole
GR
5.00
4.75
17.5-in. bit
4.50
4.25
4.00
Correction
factor
14.75-in. bit
3.75
13.5-in. bit
3.50
12.25-in. bit
3.25
10.625-in. bit
3.00
9.875-in. bit
2.75
2.50
8
9
10
11
12
13
14
15
16
17
18
19
Mud weight (lbm/gal)
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to provide a correction factor for gamma ray values
measured with the PowerPulse 8.25-in. normal-flow MWD telemetry
system. These environmental corrections for mud weight and bit
size are already applied to the gamma ray presented on the logs.
Description
Enter the chart with the mud weight on the x-axis and move upward
to intersect the appropriate bit size. Interpolate between lines as
necessary. At the intersection point, move hori­zontally left to the y-axis
to read the appropriate correction factor that the PowerPulse gamma
ray value was multiplied by to obtain the corrected GR value in gAPI
units.
31
Gamma Ray—LWD
PowerPulse* Gamma Ray—8.25-in. High-Flow Tool
GR-11
Borehole Correction for Open Hole
4.25
GR
4.00
3.75
17.5-in. bit
3.50
3.25
Correction
factor
14.75-in. bit
13.5-in. bit
3.00
12.25-in. bit
2.75
10.625-in. bit
2.50
9.875-in. bit
2.25
2.00
1.75
8
9
10
11
12
13
14
15
16
17
18
19
Mud weight (lbm/gal)
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to provide a correction factor for gamma ray values
measured with the PowerPulse 8.25-in. high-flow MWD telemetry
system. These environmental corrections for mud weight and bit
size are already applied to the gamma ray presented on the logs.
32
Description
Enter the chart with the mud weight on the x-axis and move upward
to intersect the appropriate bit size. Interpolate between lines as
necessary. At the intersection point, move horizontally left to the
y-axis to read the correction factor that the PowerPulse gamma ray
value was multiplied by to obtain the corrected gamma ray value in
gAPI units.
Gamma Ray—LWD
PowerPulse* Gamma Ray—9-in. Tool
GR-12
Borehole Correction for Open Hole
7.50
GR
7.00
6.50
6.00
22-in. bit
5.50
Correction
factor
5.00
17.5-in. bit
4.50
14.75-in. bit
4.00
13.5-in. bit
12.25-in. bit
3.50
10.625-in. bit
3.00
2.50
8
9
10
11
12
13
14
15
16
17
18
19
Mud weight (lbm/gal)
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to provide a correction factor for gamma ray values
measured with the PowerPulse 9-in. MWD telemetry system. These
environmental corrections for mud weight and bit size are already
applied to the gamma ray presented on the logs.
Description
Enter the chart with the mud weight on the x-axis and move upward
to intersect the appropriate bit size. Interpolate between lines as
necessary. At the intersection point, move horizontally left to the
y-axis to read the correction factor that the PowerPulse gamma ray
value was multiplied by to obtain the corrected gamma ray value in
gAPI units.
33
Gamma Ray—LWD
PowerPulse* Gamma Ray—9.5-in. Normal-Flow Tool
GR-13
Borehole Correction for Open Hole
8.00
GR
7.50
7.00
22-in. bit
6.50
6.00
17.5-in. bit
Correction
factor
5.50
5.00
14.75-in. bit
13.5-in. bit
4.50
12.25-in. bit
4.00
10.625-in. bit
3.50
3.00
8
9
10
11
12
13
14
15
16
17
18
19
Mud weight (lbm/gal)
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to provide a correction factor for gamma ray values
measured with the PowerPulse 9.5-in. normal-flow MWD telemetry
system. These environmental corrections for mud weight and bit
size are already applied to the gamma ray presented on the logs.
34
Description
Enter the chart with the mud weight on the x-axis and move upward
to intersect the appropriate bit size. Interpolate between lines as
necessary. At the intersection point, move horizontally left to the
y-axis to read the correction factor that the PowerPulse gammma ray
value was multiplied by to obtain the corrected gamma ray value in
gAPI units.
Gamma Ray—LWD
PowerPulse* Gamma Ray—9.5-in. High-Flow Tool
GR-14
Borehole Correction for Open Hole
8.00
GR
22-in. bit
7.50
7.00
6.50
6.00
5.50
Correction
factor
17.5-in. bit
5.00
4.50
14.75-in. bit
4.00
13.5-in. bit
3.50
12.25-in. bit
3.00
10.625-in. bit
2.50
2.00
8
9
10
11
12
13
14
15
16
17
18
19
Mud weight (lbm/gal)
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to provide a correction factor for gamma ray values
measured by the PowerPulse 9.5-in. high-flow MWD telemetry system. These environmental corrections for mud weight and bit size
are already applied to the gamma ray presented on the logs.
Description
Enter the chart with the mud weight on the x-axis and move upward
to intersect the appropriate bit size. Interpolate between lines as
necessary. At the intersection point, move horizontally left to the
y-axis to read the correction factor that the PowerPulse gamma ray
value was multiplied by to obtain the corrected gamma ray value in
gAPI units.
35
Gamma Ray—LWD
geoVISION675* GVR* Gamma Ray—6.75-in. Tool
GR-15
Borehole Correction for Open Hole
2.75
GR
2.50
2.25
2.00
Correction
factor
12.25-in. bit
1.75
1.50
10.625-in. bit
1.25
9.875-in. bit
0.75
8.75-in. bit
8.5-in. bit
1.00
8
9
10
11
12
13
14
15
16
17
18
19
Mud weight (lbm/gal)
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to provide a correction factor for gamma ray
values measured with the GVR resistivity sub of the geoVISION 6 3⁄4-in.
MWD/LWD imaging system. These environmental corrections for
mud weight and bit size are already applied to the gamma ray
presented on the logs.
36
Description
Enter the chart with the mud weight on the x-axis and move upward
to intersect the appropriate bit size. Interpolate between lines as
necessary. At the intersection point, move horizontally left to the
y-axis to read the correction factor that the GVR gamma ray value was
multiplied by to obtain the corrected gamma ray value in gAPI units.
Gamma Ray—LWD
RAB* Gamma Ray—8.25-in. Tool
GR-16
Borehole Correction for Open Hole
3.00
GR
2.75
2.50
17.5-in. bit
2.25
2.00
Correction
factor
1.75
14.75-in. bit
1.50
13.5-in. bit
1.25
12.25-in. bit
1.00
10.625-in. bit
9.875-in. bit
0.75
0.50
8
9
10
11
12
13
14
15
16
17
18
19
Mud weight (lbm/gal)
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to provide a correction factor for gamma ray values
measured with the RAB Resistivity-at-the-Bit 8.25-in. tool. These environmental corrections for mud weight and bit size are already
applied to the gamma ray presented on the logs.
Description
Enter the chart with the mud weight on the x-axis and move upward
to intersect the appropriate bit size. Interpolate between lines as
necessary. At the intersection point, move horizontally left to the
y-axis to read the correction factor that the RAB gamma ray value
was multiplied by to obtain the corrected gamma ray value in gAPI
units.
37
Gamma Ray—LWD
arcVISION475* Gamma Ray—4.75-in. Tool
GR-19
Borehole Correction for Open Hole
1.75
GR
1.50
8.5-in. bit
Correction
factor
1.25
7-in. bit
6-in. bit
1.00
0.75
8
9
10
11
12
13
14
15
16
17
18
19
Mud weight (lbm/gal)
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to provide a correction factor for gamma ray values
measured with the arcVISION475 43⁄4-in. drill collar resistivity tool.
These environmental corrections for mud weight and bit size are
already applied to the gamma ray presented on the logs.
38
Description
Enter the chart with the mud weight on the x-axis and move upward
to intersect the appropriate bit size. Interpolate between lines as
necessary. At the intersection point, move horizontally left to the
y-axis to read the correction factor that the arcVISION475 gamma
ray value was multiplied by to obtain the corrected gamma ray value
in gAPI units.
Gamma Ray—LWD
arcVISION675* Gamma Ray—6.75-in. Tool
GR-20
Borehole Correction for Open Hole
3.50
GR
3.25
3.00
2.75
2.50
12.25-in. bit
2.25
Correction
factor
2.00
10.625-in. bit
1.75
1.50
9.875-in. bit
1.25
8.75-in. bit
8.5-in. bit
1.00
0.75
0.50
8
9
10
11
12
13
14
15
16
17
18
19
Mud weight (lbm/gal)
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to provide a correction factor for gamma ray values
measured with the arcVISION675 63⁄4-in. drill collar resistivity tool.
These environmental corrections for mud weight and bit size are
already applied to the gamma ray presented on the logs.
Description
Enter the chart with the mud weight on the x-axis and move upward
to intersect the appropriate bit size. Interpolate between lines
as necessary. At the intersection point, move horizontally left to
the y-axis to read the appropriate correction factor that the
arcVISION675 gamma ray value was multiplied by to obtain
the corrected gamma ray value in gAPI units.
39
Gamma Ray—LWD
arcVISION825* Gamma Ray—8.25-in. Tool
GR-21
Borehole Correction for Open Hole
3.00
GR
2.75
2.50
17.5-in. bit
2.25
2.00
Correction
factor
1.75
14.75-in. bit
1.50
13.5-in. bit
1.25
12.25-in. bit
10.625-in. bit
1.00
9.875-in. bit
0.75
0.50
8
9
10
11
12
13
14
15
16
17
18
19
Mud weight (lbm/gal)
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to provide a correction factor for gamma ray values
measured with the arcVISION825 81⁄4-in. drill collar resistivity tool.
These environmental corrections for mud weight and bit size are
already applied to the gamma ray presented on the logs.
40
Description
Enter the chart with the mud weight on the x-axis and move upward
to intersect the appropriate bit size. Interpolate between lines as
necessary. At the intersection point, move horizontally left to
the y-axis and read the appropriate correction factor that the
arcVISION825 gamma ray value was multiplied by to obtain
the corrected gamma ray value in gAPI units.
Gamma Ray—LWD
arcVISION900* Gamma Ray—9-in. Tool
GR-22
Borehole Correction for Open Hole
5.5
GR
5.0
4.5
22-in. bit
4.0
3.5
Correction
factor
3.0
2.5
17.5-in. bit
2.0
14.75-in. bit
1.5
13.5-in. bit
12.25-in. bit
10.625-in. bit
1.0
0.5
8
9
10
11
12
13
14
15
16
17
18
19
Mud weight (lbm/gal)
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to provide a correction factor for gamma ray values
measured with the arcVISION900 9-in. drill collar resistivity tool.
These environmental corrections for mud weight and bit size are
already applied to the gamma ray presented on the logs.
Description
Enter the chart with the mud weight on the x-axis and move upward
to intersect the appropriate bit size. Interpolate between lines as
necessary. At the intersection point, move horizontally left to
the y-axis and read the appropriate correction factor that the
arcVISION900 gamma ray value was multiplied by to obtain the
corrected gamma ray value in gAPI units.
41
Gamma Ray—LWD
arcVISION475* Gamma Ray—4.75-in. Tool
GR-23
Potassium Correction for Open Hole
100
GR
90
80
70
20 ppg
60
Correction
subtracted
for 5-wt%
potassium
(gAPI)
18 ppg
50
16 ppg
12 ppg
14 ppg
40
9 ppg
10 ppg
8.3 ppg
30
20
10
0
6
8
10
12
14
16
18
Hole size (in.)
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to provide a correction that is subtracted from
the borehole-corrected gamma ray from the arcVISION475 43⁄4-in.
tool. Environmental corrections for mud weight and bit size are
already applied to the gamma ray presented on the logs.
42
Description
This chart is for illustrative purposes only. The indicated correction
is already applied to the gamma ray log.
To determine the correction that was applied to the log output,
enter the chart with the borehole size on the x-axis and move upward
to intersect the downhole mud weight. From the intersection point
move horizontally left to read the correction in gAPI units that was
subtracted from the borehole-corrected data.
Charts GR-24 through GR-26 are similar to Chart GR-23 for
different arcVISION tool sizes.
Gamma Ray—LWD
arcVISION675* Gamma Ray—6.75-in. Tool
GR-24
Potassium Correction for Open Hole
50
GR
20 ppg
45
18 ppg
40
16 ppg
35
14 ppg
30
Correction
subtracted
for 5-wt%
potassium
(gAPI)
12 ppg
25
10 ppg
20
9 ppg
8.3 ppg
15
10
5
0
8.5
9.0
9.5
10.0
10.5
11.0
11.5
12.0
12.5
13.0
Hole size (in.)
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to provide a correction that is subtracted from
the borehole-corrected gamma ray from the arcVISION675 63⁄4-in.
tool. Environmental corrections for mud weight and bit size are
already applied to the gamma ray presented on the logs.
Description
This chart is for illustrative purposes only. The indicated correction
is already applied on the gamma ray log.
To determine the correction that was applied to the log output,
enter the chart with the borehole size on the x-axis and move
upward to intersect the downhole mud weight. From the intersection
point move horizontally left to read the correction in gAPI units that
was subtracted from the borehole-corrected data.
43
Gamma Ray—LWD
arcVISION825* Gamma Ray—8.25-in. Tool
GR-25
Potassium Correction for Open Hole
100
GR
90
80
20 ppg
70
Correction
subtracted
for 5-wt%
potassium
(gAPI)
18 ppg
16 ppg
60
14 ppg
50
12 ppg
40
10 ppg
9 ppg
30
8.3 ppg
20
10
0
0
10
12
14
16
18
20
22
Hole size (in.)
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to provide a correction that is subtracted from
the borehole-corrected gamma ray from the arcVISION825 81⁄4-in.
tool. Environmental corrections for mud weight and bit size are
already applied to the gamma ray presented on the logs.
44
Description
This chart is for illustrative purposes only. The indicated correction
is already applied on the gamma ray log.
To determine the correction that was applied to the log output,
enter the chart with the borehole size on the x-axis and move upward
to intersect the downhole mud weight. From the intersection point
move horizontally left to read the correction in gAPI units that was
subtracted from the borehole-corrected data.
Gamma Ray—LWD
arcVISION900* Gamma Ray—9-in. tool
GR-26
Potassium Correction for Open Hole
120
GR
100
20 ppg
18 ppg
80
16 ppg
Correction
subtracted
for 5-wt%
potassium
(gAPI)
14 ppg
60
12 ppg
10 ppg
40
9 ppg
8.3 ppg
20
0
9
10
11
12
13
14
15
16
17
18
19
20
Hole size (in.)
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to provide a correction that is subtracted from
the borehole-corrected gamma ray from the arcVISION900 9-in. tool.
Environmental corrections for mud weight and bit size are already
applied to the gamma ray presented on the logs.
Description
This chart is for illustrative purposes only. The indicated correction
is already applied on the gamma ray log.
To determine the correction that was applied to the log output,
enter the chart with the borehole size on the x-axis and move upward
to intersect the downhole mud weight. From the intersection point
move horizontally left to read the correction curve in gAPI units that
was subtracted from the borehole-corrected data.
45
Gamma Ray—LWD
EcoScope* Integrated LWD Gamma Ray—6.75-in. Tool
GR-27
Borehole Correction for Open Hole
3.00
GR
2.75
2.50
2.25
2.00
Correction
factor
1.75
12.25-in. bit
1.50
10.625-in. bit
9.875-in. bit
1.25
8.75-in. bit
8.5-in. bit
1.00
0.75
0.50
8
9
10
11
12
13
14
15
16
17
18
19
Mud weight (lbm/gal)
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to provide a correction factor for gamma ray
values measured with the EcoScope 6.75-in. Integrated LWD tool.
These environmental corrections for mud weight and bit size are
normally already applied to the gamma ray presented on the field
logs.
46
Description
Enter the chart with the mud weight on the x-axis and move upward
to intersect the appropriate bit size. Interpolate between lines as
necessary. At the intersection point, move horizontally left to the
y-axis to read the appropriate correction factor that the EcoScope
6.75-in. gamma ray value was multiplied by to obtain the corrected
gamma ray value in gAPI units.
Gamma Ray—LWD
Ray–Wireline
EcoScope* Integrated LWD Gamma Ray—6.75-in. Tool
GR-28
Potassium Correction for Open Hole
50
GR
45
40
35
20 ppg
30
Correction
subtracted
for 5-wt%
potassium
(gAPI)
18 ppg
16 ppg
25
14 ppg
20
12 ppg
10 ppg
15
9 ppg
8.3 ppg
10
5
0
8.5
9.0
9.5
10.0
10.5
11.0
11.5
12.0
12.5
13.0
Hole size (in.)
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to illustrate the potassium correction that is subtracted from the borehole-corrected gamma ray from the EcoScope
6.75-in. Integrated LWD tool. Environmental corrections for mud
weight, bit size, and potassium are normally already applied to the
gamma ray presented on the field logs.
Description
This chart is for illustrative purposes only. The indicated correction
is already applied on the gamma ray log. The chart shows the correction for a typical 5-wt% potassium concentration.
To determine the correction that was applied to the log output,
enter the chart with the borehole size on the x-axis and move upward
to intersect the downhole mud weight. From the intersection point
move horizontally left to read the correction curve in gAPI units that
was subtracted from the borehole-corrected data.
47
Spontaneous Potential—Wireline
Rweq Determination from ESSP
Purpose
This chart and nomograph are used to calculate the equivalent formation water resistivity (Rweq) from the static spontaneous potential
(ESSP) measured in clean formations. The value of Rweq is used in
Chart SP-2 to determine the resistivity of the formation water (Rw).
Rw is used in Archie’s water saturation equation.
SP
Description
Enter the chart with ESSP in millivolts on the x-axis and move upward
to intersect the appropriate temperature line. From the intersection
point move horizontally to intersect the right y-axis for Rmfeq/Rweq.
From this point, draw a straight line through the equivalent mud filtrate resistivity (Rmfeq) point on the Rmfeq nomograph to intersect the
value of Rweq on the far-right nomograph.
The spontaneous potential (SP) reading corrected for the effect
of bed thickness (ESPcor) from Chart SP-4 can be substituted for ESSP.
48
Example
First determine the value of Rmfeq:
■ If Rmf at 75°F is greater than 0.1 ohm-m, correct Rmf
to the formation temperature by using Chart Gen-6,
and use Rmfeq = 0.85Rmf.
■ If Rmf at 75°F is less than 0.1 ohm-m, use Chart SP-2
to derive a value of Rmfeq at formation temperature.
Given:
ESSP = –100 mV at 250°F and resistivity of the mud
filtrate (Rmf) = 0.7 ohm-m at 100°F, converted to 0.33
at 250°F.
Find:
Rweq at 250°F.
Answer:
Rmfeq = 0.85Rmf = 0.85 × 0.33 = 0.28 ohm-m.
Draw a straight line from the point on the Rmfeq /Rweq line
that corresponds to the intersection of ESSP = –100 mV and
the interpolated 250°F temperature curve through the
value of 0.28 ohm-m on the Rmfeq line to the Rweq line to
determine that the value of Rweq is 0.025 ohm-m.
The value of Rmfeq /Rweq can also be determined from the
equation
ESSP = K c log (Rmfeq /Rweq),
where K c is the electrochemical spontaneous potential
coefficient:
K c = 61 + (0.133 × Temp°F)
K c = 65 + (0.24 × Temp°C).
Spontaneous Potential—Wireline
Rweq Determination from ESSP
SP-1
(former SP-1)
Rweq
(ohm-m)
0.001
SP
0.005
Rmfeq /Rweq
0.3
0.3
0.4
0.4
0.5
0.6
0.6
0.8
0.8
1
1
Rmfeq
(ohm-m)
0.01
0.01
0.02
0.02
0.04
0.06
2
2
3
Rmf /Rw
0.1
0.05
0.2
4
4
5
6
6
8
8
10
10
0.4
0.6
0.1
1
2
0.2
4
Formation
temperature
30
40
50
+50
0
–50
0°F
F
50
0°
40
0°F
C
0
3
0°
25 00°C
°F
2
°C
200
150
°C
°F
100
100
C
50°
0°C
20
–100
–150
Static spontaneous potential, ESSP (mV)
6
20
10
0.5
20
40
–200
40
60
1.0
100
2.0
© Schlumberger
49
Spontaneous Potential—Wireline
Rweq versus Rw and Formation Temperature
SP-2
(customary, former SP-2)
0.001
500°F
400°F
300°F
0.002
200°F
SP
150°F
0.005
100°F
75°F
0.01
Saturation
0.02
Rweq or Rmfeq
(ohm-m)
0.05
0.1
0.2
500°F
400°
F
0.5
°F
75
at
Cl
Na
1.0
2.0
0.005
300°
F
200°
F
150
°F
100
°
75° F
F
0.01
0.02 0.03
0.05
0.1
0.2
0.3
0.5
1.0
2
3
4 5
Rw or Rmf (ohm-m)
© Schlumberger
Purpose
This chart is used to convert equivalent water resistivity (Rweq ) from
Chart SP-1 to actual water resistivity (Rw). It can also be used to convert the mud filtrate resistivity (Rmf) to the equivalent mud filtrate
resistivity (Rmfeq ) in saline mud. The metric version of this chart is
Chart SP-3 on page 49.
Description
The solid lines are used for predominantly NaCl waters. The dashed
lines are approximations for “average” fresh formation waters (for
which the effects of salts other than NaCl become significant).
50
The dashed lines can also be used for gypsum-base mud filtrates.
Example
Given:
Find:
Answer:
From Chart SP-1, Rweq = 0.025 ohm-m at 250°F in
predominantly NaCl water.
Rw at 250°F.
Enter the chart at the Rweq value on the y-axis and move
horizontally right to intersect the solid 250°F line. From
the intersection point, move down to find the Rw value
on the x-axis. Rw = 0.03 ohm-m at 250°F.
Spontaneous Potential—Wireline
Rweq versus Rw and Formation Temperature
SP-3
(metric, former SP-2m)
0.001
250°C
200°C
0.002
150°C
100°C
SP
75°C
0.005
50°C
25°C
0.01
Saturation
0.02
Rweq or Rmfeq
(ohm-m)
0.05
0.1
0.2
250°C
200°
C
150°
C
100°
C
75°C
50°
C
25°
C
0.5
°C
25
at
Cl
Na
1.0
2.0
0.005
0.01
0.02
0.03
0.05
0.1
0.2
0.3
0.5
1.0
2
3
4 5
Rw or Rmf (ohm-m)
© Schlumberger
Purpose
This chart is the metric version of Chart SP-2 for converting equivalent water resistivity (Rweq) from Chart SP-1 to actual water resistivity (Rw). It can also be used to convert the mud filtrate resistivity (Rmf)
to the equivalent mud filtrate resistivity (Rmfeq) in saline mud.
(for which the effects of salts other than NaCl become significant).
The dashed lines can also be used for gypsum-base mud filtrates.
Description
The solid lines are used for predominantly NaCl waters. The dashed
lines are approximations for “average” fresh formation waters
Find:
Answer:
Example
Given:
From Chart SP-1, Rweq = 0.025 ohm-m at 121°C in
predominantly NaCl water.
Rw at 121°C.
Rw = 0.03 ohm-m at 121°C.
51
Spontaneous Potential—Wireline
Bed Thickness Correction—Open Hole
Purpose
Chart SP-4 is used to correct the SP reading from the well log for
the effect of bed thickness. Generally, water sands greater than
20 ft in thickness require no or only a small correction.
Description
Chart SP-4 incorporates correction factors for a number of conditions that can affect the value of the SP in water sands.
SP
52
The appropriate chart is selected on the basis of resistivity, invasion, hole diameter, and bed thickness. First, select the row of charts
with the most appropriate value of the ratio of the resistivity of shale
(Rs) to the resistivity of mud (Rm). On that row, select a chart for no
invasion or for invasion for which the ratio of the diameter of invasion
to the diameter of the wellbore (di /dh) is 5. Enter the x-axis with
the value of the ratio of bed thickness to wellbore diameter (h/dh).
Move upward to intersect the appropriate curve of the ratio of the
true formation resistivity to the resistivity of the mud (Rt /Rm) for
no invasion or the ratio of the resistivity of the flushed zone to the
resistivity of the mud (Rxo /Rm) for invaded zones, interpolating
between the curves as necessary. Read the ratio of the SP read from
the log to the corrected SP (ESP/ESPcor) on the y-axis for the point of
intersection. Calculate ESPcor = ESP/(ESP/ESPcor). The value of ESPcor
can be used in Chart SP-1 for ESSP.
Spontaneous Potential—Wireline
Potential-Wireline
Bed Thickness Correction—Open Hole
SP-4
(former SP-3)
Invasion, di /dh = 5
No Invasion
Rs
=1
Rm
Rxo = 0.2Rt
1.0
1
5 2
10
0.8
0.1
0.8
0.6
2
0.4
0.2
Rt /Rm
Rxo /Rm
40 30 20 15 10 7.5
h/dh
1.0
5
10
0.8
5
1.0
2
0.8
0.4
500
1.0
Rxo /Rm
5
0.8
0.6
0.4
0.4
200
Rt /Rm
5
10
0.6
20
0.4
50
0.2
100
40 30 20 15 10 7.5
h/dh
2
5
0.8
Rxo /Rm
5
500
40 30 20 15 10 7.5
h/dh
1.0
1
5
10
20
0.8
10
20
0.6
200
200
500
1.0
50
Rxo /Rm
5
100
0.2
5
2
0.6
50
0.4
100
Rxo /Rm
5
500
1,000
40 30 20 15 10 7.5
h/dh
200
0.2
200
100
200
500
40 30 20 15 10 7.5
h/dh
50
0.4
20
0.2
500
1,000
40 30 20 15 10 7.5
h/dh
2
10
100
0.2
100
Rxo /Rm
5
0.6
50
ESP /ESPcor
0.2
1
2
0.8
20
5
50
1.0
5 2
10
0.8
10
50
100
200
40 30 20 15 10 7.5
h/dh
1
5
0.4
20
0.2
200
1.0
40 30 20 15 10 7.5
h/dh
20
10
100
5
5
5
0.4
Rxo /Rm
0.5
1
2
0.6
100
200
200
40 30 20 15 10 7.5
h/dh
0.8
2
50
40 30 20 15 10 7.5
h/dh
1.0
0.5
0.6
Rt /Rm
5
1
0.6
0.2
Rxo /Rm
50
0.2
100
0.2
20
ESP /ESPcor
0.2
100
40 30 20 15 10 7.5
h/dh
0.4
50
10
20
50
0.2
200
20
20
0.4
SP
10
0.6
10
5
100
Rs
= 20
Rm
0.6
0.5
0.5
21
5
0.8
5
1
0.4
Rs
=5
Rm
0.5
1
2
0.8
0.2
0.6
50
Rxo = 5Rt
1.0
1.0
20
ESP /ESPcor
Rxo = Rt
1.0
Rxo /Rm
5
500
1,000
40 30 20 15 10 7.5
h/dh
5
© Schlumberger
53
Spontaneous Potential—Wireline
Bed Thickness Correction—Open Hole (Empirical)
SP-5
(customary, former SP-4)
8-in. Hole; 33⁄8 -in. Tool, Centered
100
1.0
di (in.)
20
90
30
30
SP
30
Ri
Rm
35
30
80
35
30
40
ESSP
(%)
5
40
70
1.5
60
Correction
factor
50
20
2.0
40
50
2.5
3.0
30
100
3.5
4.0
20
200
70
50
40
30
20
15
10 9 8 7 6
5
4
5.0
3
Bed thickness, h (ft)
© Schlumberger
Purpose
This chart is used to provide an empirical correction to the SP for
the effects of invasion and bed thickness. The correction was obtained
by averaging a series of thin-bed corrections in Reference 4. The
resulting value of static spontaneous potential (ESSP) can be used
in Chart SP-1.
Description
This chart considers bed thickness (h) as a variable, and the ratio of
the resistivity of the invaded zone to the resistivity of the mud (Ri /Rm)
and the diameter of invasion (di ) as parameters of fixed value. The
borehole diameter is fixed at 8 in. and the tool size at 33⁄8 in.
54
To obtain the correction factor, enter the chart on the x-axis with
the value of h. Move upward to the appropriate di curve for the range
of Ri /Rm. The correction factor on the y-axis corresponding to the
intersection point is multiplied by the SP from the log to obtain the
corrected SP.
Spontaneous Potential—Wireline
Bed Thickness Correction—Open Hole (Empirical)
SP-6
(metric, former SP-4m)
200-mm Hole; 86-mm Tool, Centered
100
1.0
di (m)
0.5
90
5
0.7
0.7
0.7
5
5
80
0.8
5
0.7
5
0.8
0.7
8
5
1.0
70
1.5
1.0
ESSP
(%)
SP
Ri
Rm
60
Correction
factor
50
20
40
50
2.0
2.5
3.0
30
100
20
200
20
15
10
5
3
2
3.5
4.0
5.0
1
Bed thickness, h (m)
© Schlumberger
Purpose
This chart is the metric version of Chart SP-5 for providing an empirical correction to the SP for the effects of invasion and bed thickness. The correction was obtained by averaging a series of thin-bed
corrections in Reference 4. The resulting value of ESSP can be used
in Chart SP-1.
Description
This chart considers bed thickness (h) as a variable, and R i /Rm and
di as parameters of fixed value. The borehole diameter is fixed at
203 mm and the tool size at 86 mm.
55
General
Density—Wireline,
LWD
Porosity Effect on Photoelectric Cross Section
Pe
2
1
3
φt
4
5
6
0.5 0.4 0.3 0.2 0.1 0
Dens-1
Porosity Effect on Pe
Matrix
Quartz
Dens
Calcite
Water Gas
Quartz Dolomite
Dolomite
Specific
gravity
ϕt
100% H2O
100% CH4
0.00
0.35
0.00
0.35
0.00
0.35
—
1.81
1.54
5.08
4.23
3.14
2.66
1.00
1.81
1.76
5.08
4.96
3.14
3.07
0.10
Calcite
© Schlumberger
Purpose
This chart and accompanying table illustrate the effect that porosity,
matrix, formation water, and methane (CH4) have on the recorded
photoelectric cross section (Pe).
Description
The table lists the data from which the chart was made. As the
porosity increases the effect is greater for each mineral. Calcite has
the largest effect in the presence of gas or water as the porosity
increases.
56
Enter the chart with the total porosity (ϕt) from the log and move
downward to intersect the angled line. From this point move
to the left and intersect the line representing the appropriate matrix
material: quartz, dolomite, or calcite minerals. From this intersection
move upward to read the correct Pe.
Density—Wireline, LWD
Apparent Log Density to True Bulk Density
Dens-2
0.14
Add correction
from y-axis to ρlog
to obtain true
bulk density, ρb
Salt (NaCI)
0.12
Sylvite (KCI)
0.10
Aluminum
Magnesium
ρb – ρlog
(g/cm3)
Dens
φ = 40%
0.08
Dolomite
0.06
Sandstone
Limestone
0.04
Low-pressure gas
or air in pores
An
th
ra
cit
e
Co
al
0.02
us
no
mi
tu
Bi
0
Sandstone + water
φ = 40%
–0.02
φ=0
Limestone + water
Dolomite + water
Gypsum
–0.04
1
Gem-1
2
ρlog (g/cm3)
3
© Schlumberger
Purpose
This chart is used to determine the true bulk density (ρb) from the
“apparent” recorded log value (ρlog).
sandstone, limestone, and dolomite with water in the pores. This
shows that there is a slight correction for water-filled formations
from the log density value.
Description
Enter the chart with the log density reading on the x-axis and move
upward to intersect the mineral line that best represents the formation. At this point, move horizontally left to read the value to be added
to the log density. The individual mineral points reflect the log-derived
density and the correction factor to be added or subtracted from the
log value to obtain the true density of that mineral.
The long diagonal lines representing zero porosity at the lower
right and 40% porosity at the upper left are for dry gas in the forma­
tion. The three points at the lower right of the diagonal lines rep­
resent zero dry gas in the formation and are the endpoints for
Example
Given:
Log density = 2.40 g/cm3 in a sandstone formation
(dry gas).
Find:
Corrected bulk density.
Answer:
Enter the x-axis at 2.4 g/cm3 and move upward to intersect the sandstone line. The correction from the y-axis is
0.02 g/cm3. The correction value is added to the log density to obtain the true value of the bulk density:
2.40 + 0.02 = 2.42 g/cm3.
57
Neutron—Wireline
Dual-Spacing Compensated Neutron Tool Charts
Neu
This section contains interpretation charts to cover developments in
compensated neutron tool (CNT) porosity transforms, environmental
corrections, and porosity and lithology determination.
CSU* software (versions CP-30 and later) and MAXIS* ­software
compute three t­ hermal porosities: NPHI, TNPH, and NPOR.
NPHI is the “classic NPHI,” computed from instantaneous near
and far count rates, using “Mod-8” ratio-to-porosity transform with
a caliper correction.
TNPH is computed from deadtime-corrected, depth- and
­resolution-matched count rates, using an improved ratio-to-porosity
transform and performing a complete set of environmental corrections
in real time. These corrections may be turned on or off by the field
engineer at the wellsite. For more information see Reference 32.
NPOR is computed from the near-detector count rate and TNPH
to give an enhanced resolution porosity. The accuracy of NPOR is
equivalent to the accuracy of TNPH if the environmental effects on
the near detector change less rapidly than the formation porosity.
For more information on enhanced resolution processing, see
Reference 35.
Cased hole CNT logs are recorded on NPHI, computed from
instantaneous near and far count rates, with a cased hole ratio-toporosity transform.
58
Using the Neutron Correction Charts
For logs labeled NPHI:
1. Enter Chart Neu-5 with NPHI and caliper reading to convert to
uncorrected neutron porosity.
2. Enter Charts Neu-1 and Neu-3 to obtain corrections for each
environmental effect. Corrections are summed with the uncorrected porosity to give a corrected value.
3. Use crossplot Charts Por-11 and Por-12 for porosity and lithology
determination.
For logs labeled TNPH or NPOR, the CSU wellsite surface
instrumentation and MAXIS software have applied environmental
correc­tions as indicated on the log heading. If the CSU and MAXIS
software has applied all ­corrections, TNPH or NPOR can be used
directly with the crossplot charts. In this case:
1. Use crossplot Charts Por-11 and Por-12 to determine ­porosity
and lithology.
Neutron—Wireline
Compensated Neutron Tool
Environmental Correction—Open Hole
Purpose
Chart Neu-1 is used to correct the compensated neutron log porosity
index if the caliper correction was not applied. If the caliper correction is applied, it must be “backed out” to use this chart.
Description
This chart is used only if the caliper correction was not applied
to the logged data. The parameter section of the log heading lists
whether correction was applied.
Example 1: Backed-Out Correction of TNPH Porosity
Given:
Thermal neutron porosity (TNPH) from the log = 32 p.u.
(apparent limestone units) and borehole size = 12 in.
Find:
Uncorrected TNPH with the correction backed out.
Answer:
Enter the top chart for actual borehole size at the intersection point of the standard conditions 8-in. horizontal
line and 32 p.u. on the scale above the chart.
From this point, follow the closest trend line to intersect
the 12-in. line for the borehole size.
The intersection is the uncorrected TNPH value of 34 p.u.
To use the uncorrected value on Chart Neu-1, draw a vertical line from this intersection through the remainder of
the charts, as shown by the red line.
Example 2: Environmentally Corrected THPH
Given:
Neutron porosity of 32 p.u. (apparent limestone units),
without environmental correction, 12-in. borehole, 1⁄4-in.
thick mudcake, 100,000-ppm borehole salinity, 11-lbm/gal
natural mud weight (water-base mud [WBM]), 150°F
borehole temperature, 5,000-psi pressure (WBM), and
100,000-ppm formation salinity.
Find:
Environmentally corrected TNPH porosity.
Answer:
If there is standoff (which is not uncommon), use Chart
Neu-3. Then use Chart Neu-1 by drawing a vertical
line through the charts for the previously determined
backed-out (uncorrected) 34-p.u. neutron porosity
value.
On each environmental correction chart, enter the y-axis
at the given value and move horizontally left to intersect
the porosity value vertical line.
For example, on the mudcake thickness chart the line
extends from 1⁄4 in. on the y-axis.
At the intersection point, move parallel to the closest
blue trend line to intersect the standard conditions, as
indicated by the bullet.
The point of intersection with the standard conditions
for the chart is the value of porosity corrected for the
particular environment. The change in porosity value
(either positive or negative) is summed for the charts
and referred to as delta porosity (Δϕ).
The Δϕ net correction applied to the uncorrected log neutron
porosity is listed in the table for the two examples.
CNT Neutron Porosity Correction Examples
Example 1
Correction
Example 2
Log porosity
32 p.u.
Borehole size
12 in.
–2
1
⁄4 in.
0
Mudcake thickness
Borehole salinity
100,000 ppm
+1
Mud weight
11 lbm/gal
+2
Borehole temperature
150°F
+4
Wellbore pressure
5,000 psi
–1
Formation salinity
100,000 ppm
–3
Standoff (from Chart Neu-3)
1 in.
–4
Net environmental correction
–1
Backed-out corrected porosity
34 p.u.
Environmentally corrected porosity
33 p.u.
Net correction
Backed-out, environmentally corrected porosity
Δϕ
–3
31 p.u.
continued on next page
59
Neu
Neutron—Wireline
Compensated Neutron Tool
Neu-1
Environmental Correction—Open Hole
(customary, former Por-14c)
Neutron log porosity index (apparent limestone porosity in p.u.)
0
Actual borehole size
(in.)
10
20
30
40
50
24
20
16
12
8
4
•
1.0
Mudcake thickness
(in.)
0.5
0
•
250
Neu
Borehole salinity
(1,000 × ppm)
0
Natural
Mud weight
(lbm/gal)
Barite
•
13
12
11
10
9
8
•
18
16
14
12
10
8
•
300
Borehole temperature
(°F)
•
50
Pressure
(1,000 × psi)
Water-base mud
Oil-base mud
25
0
•
250
Limestone
formation salinity
(1,000 × ppm)
0
•
0
10
20
30
40
50
• Standard conditions
© Schlumberger
60
Neutron—Wireline
Compensated Neutron Tool
Neu-2
Environmental Correction—Open Hole
(metric, former Por-14cm)
Neutron log porosity index (apparent limestone porosity)
0
Actual borehole size
(mm)
10
20
30
40
50
600
500
400
300
200
100
•
25
Mudcake thickness
(mm)
12.5
0
•
250
Neu
Borehole salinity
(g/kg)
0
•
Natural
1.5
Mud density
(g/cm3)
•
1.0
Barite
2.0
1.0
Borehole temperature
(°C)
Pressure
(MPa)
Water-base mud
Oil-base mud
•
149
121
93
66
38
10
•
172
138
103
69
34
0
•
250
Limestone
formation salinity
(g/kg)
0
•
0
10
20
30
40
50
• Standard conditions
© Schlumberger
Purpose
This chart is the metric version of Chart Neu-1 for correcting the
compensated neutron tool porosity index.
61
Neutron—Wireline
Compensated Neutron Tool
Standoff Correction—Open Hole
Purpose
Chart Neu-3 is used to determine the porosity change caused by
standoff to the uncorrected thermal neutron porosity TNPH from
Chart Neu-1.
Description
Enter the appropriate borehole size chart at the estimated neutron
tool standoff on the y-axis. Move horizontally to intersect the uncorrected porosity. At the intersection point, move along the closest
trend line to the standard conditions line defined by the bullet to
the right of the chart. This point is the porosity value corrected for
tool standoff. The difference between the standoff-corrected porosity
and the uncorrected porosity is the correction itself.
Neu
62
Example
Given:
Find:
Answer:
TNPH = 34 p.u., borehole size = 12 in., and
standoff = 0.5 in.
Porosity corrected for standoff.
Draw a vertical line from the uncorrected neutron log
porosity of 34 p.u. Enter the 12-in. borehole chart at
0.5-in. standoff and move horizontally right to intersect
the vertical porosity line. From the point of intersection
move parallel to the closest trend line to intersect the
standard conditions line (standoff = 0 in.). The standoffcorrected porosity is 32 p.u. The correction is –2 p.u.
Neutron—Wireline
Compensated Neutron Tool
Neu-3
Standoff Correction—Open Hole
(customary, former Por-14d)
Neutron log porosity index (apparent limestone porosity in p.u.)
0
Actual
borehole size
10
20
30
40
50
1
6 in.
0
•
2
1
8 in.
•
0
3
2
10 in.
1
0
Neu
•
4
3
12 in.
2
1
•
0
Standoff
(in.)
18 in.
7
6
5
4
3
2
1
0
•
10
9
8
7
24 in.
6
5
4
3
2
1
0
•
0
© Schlumberger
10
20
30
40
50
• Standard conditions
63
Neutron—Wireline
Compensated Neutron Tool
Neu-4
Standoff Correction—Open Hole
(metric, former Por-14dm)
Neutron log porosity index (apparent limestone porosity)
0
Actual
borehole size
10
20
30
40
50
25
150 mm
0
•
50
25
200 mm
•
0
75
50
250 mm
25
Neu
0
•
100
75
300 mm
50
25
0
•
175
Standoff
(mm)
450 mm
150
125
100
75
50
25
0
•
250
225
200
175
600 mm
150
125
100
75
50
25
0
•
0
10
© Schlumberger
Purpose
This chart is the metric version of Chart Neu-3 for determining the
porosity change caused by standoff.
64
20
30
40
50
• Standard conditions
Neutron—Wireline
Compensated Neutron Tool
Neu-5
Conversion of NPHI to TNPH—Open Hole
(former Por-14e)
NPHI porosity index (apparent limestone porosity in p.u.)
–5
Borehole size
(in.)
0
10
20
30
40
50
24
20
16
12
8
4
•
0
10
20
30
40
50
TNPH porosity index (apparent limestone porosity in p.u.)
Neu
• Standard conditions
© Schlumberger
Purpose
This chart is used to determine the porosity change caused by the
borehole size to the neutron porosity NPHI and convert the porosity
to thermal neutron porosity (TNPH). This chart corrects NPHI only
for the borehole sizes that differ from the standard condition of 8 in.
Refer to Chart Neu-1 to complete the environmental corrections for
the TPNH value obtained.
Description
Enter the scale at the top of the chart with the NPHI porosity.
Example
Given:
Find:
Answer:
At the point of intersection of the vertical line and the
standard conditions line, move parallel to the closest
trend line to intersect the actual borehole size line.
At that intersection point move vertically down to the
bottom scale to determine the TNPH porosity corrected
only for borehole size. This value is also used to determine the change in porosity as a result of tool standoff.
TNPH = 12.5 + 5 = 17.5 p.u.
NPHI porosity = 12.5% and borehole size = 16 in.
Porosity correction for nonstandard borehole size.
Enter the chart with the uncorrected porosity value
of 12.5 at the scale at the top. Move down vertically
to intersect the standard conditions line indicated by
the bullet to the right. Enter the chart on the y-axis with
the actual borehole size at the zone of interest and move
horizontally right across the chart.
65
Neutron—Wireline
Compensated Neutron Tool
Formation Σ Correction for Environmentally Corrected TNPH—Open Hole
Neu
Purpose
This chart is used to further correct the environmentally corrected
TNPH porosity from Chart Neu-1 for the effect of the total formation capture cross section, or sigma (Σ), of the formation of interest. This correction is applied after all environmental corrections
determined with Chart Neu-1 have been applied.
Example
Given:
Description
Enter the chart with Σ for the appropriate formation along the y-axis
and the corrected TNPH porosity along the x-axis. Where the lines
drawn from these points intersect, move parallel to the closest trend
line to intersect the appropriate fresh- or saltwater line to read the
corrected porosity.
The chart at the bottom of the page is used to correct the Σcorrected porosity for salt displacement if the formation Σ is due to
salinity. However, this correction is not made if the borehole salinity
correction from Chart Neu-1 has been applied.
Answer:
66
Find:
Corrected TNPH from Chart Neu-1 = 38 p.u., Σ of the
sandstone formation = 33 c.u., and formation salinity =
150,000 ppm (indicating a freshwater formation).
TNPH porosity corrected with Chart Neu-1 and for Σ of
the formation.
Enter the appropriate chart with the Σ value on the y-axis
and the corrected TNPH value on the x-axis. At the intersection of the sigma and porosity lines, parallel the closest trend line to intersect the freshwater line. (If the
water in the formation is salty, the 250,000-ppm line
should be used.)
Move straight down from the intersection point to the
formation salinity chart at the bottom.
From the point where the straight line intersects the top
of the salinity correction chart, parallel the closest trend
line to intersect the formation salinity line.
Draw a vertical line to the bottom scale to read the corrected formation sigma TNPH porosity, which is 35 p.u.
Neutron—Wireline
Compensated Neutron Tool
Neu-6
Formation Σ Correction for Environmentally Corrected TNPH—Open Hole
(former Por-16)
Neutron log porosity index
0
10
20
30
40
50
70
60
Sandstone formation
Formation Σ (c.u.)
50
40
30
Fresh water
250,000-ppm water
20
Neu
10
0
70
60
Limestone formation
Formation Σ (c.u.)
50
40
30
Fresh water
250,000-ppm water
20
10
0
70
60
Dolomite formation
Formation Σ (c.u.)
50
40
30
Fresh water
250,000-ppm water
20
10
0
0
Formation salinity
(1,000 × ppm)
100
250
0
10
20
30
40
50
© Schlumberger
67
Neutron—Wireline
Compensated Neutron Tool
Mineral Σ Correction for Environmentally Corrected TNPH—Open Hole
Purpose
This chart is used to further correct the environmentally corrected
TNPH porosity from Chart Neu-1 for the effect of the mineral sigma
(Σ). This correction is applied after all environmental corrections
determined with Chart Neu-1 have been applied.
Description
Enter the chart for the formation type with the mineral Σ value along
the y-axis and the Chart Neu-1 corrected TNPH porosity along the
x-axis. Where lines drawn from these points intersect, move parallel to
the closest trend line to intersect the freshwater line to read the
corrected porosity on the scale at the bottom. The choice of chart
depends on the type of mineral in the formation.
Neu
68
Example
Given:
Find:
Answer:
Corrected TNPH from Chart Neu-1 = 38 p.u., sandstone
formation Σ = 35 c.u., and formation salinity =
150,000 ppm (indicating a freshwater formation).
TNPH porosity corrected with Chart Neu-1 and for the
mineral Σ.
At the intersection of the Σ and porosity value lines
move parallel to the closest trend line to intersect the
freshwater line. Move straight down to intersect the bottom prosity scale to read the TNPH porosity corrected
for mineral Σ, which is 33 p.u.
Neutron—Wireline
Compensated Neutron Tool
Neu-7
Mineral Σ Correction for Environmentally Corrected TNPH—Open Hole
(former Por-17)
Neutron log porosity index
0
10
20
30
40
50
70
60
50
Sandstone formation
Mineral Σ (c.u.)
40
30
Neu
20
10
Fresh water
0
70
60
50
Limestone formation
Mineral Σ (c.u.)
40
30
20
10
Fresh water
0
70
60
50
Dolomite formation
Mineral Σ (c.u.)
40
30
20
10
Fresh water
0
0
10
20
30
40
50
© Schlumberger
69
Neutron—Wireline
General
Compensated Neutron Tool
Fluid Σ Correction for Environmentally Corrected TNPH—Open Hole
Purpose
This chart is used to correct the environmentally corrected TNPH
porosity from Chart Neu-1 for the effect of the fluid sigma (Σ) in
the formation. This correction is applied after all environmental
corrections determined with Chart Neu-1 have been applied.
Neu
Description
Enter the appropriate formation chart with the formation fluid Σ
value on the y-axis and the Chart Neu-1 corrected TNPH porosity on
the x-axis. Where the lines drawn from these points intersect, move
parallel to the closest trend line to intersect the appropriate freshor saltwater line. If the borehole salinity correction from Chart Neu-1
has not been applied, from this point extend a line down to intersect
the formation salinity chart at the bottom. Move parallel to the
closest trend line to intersect the formation salinity line. Move
straight down to read the corrected porosity on the scale below
the chart.
70
Example
Given:
Find:
Answer:
Corrected TNPH from Chart Neu-1 = 30 p.u. (without
borehole salinity correction), fluid Σ = 80 c.u., fluid
salinity = 150,000 ppm, and sandstone formation.
TNPH corrected with Chart Neu-1 and for fluid Σ.
At the intersection of the fluid Σ and Chart Neu-1
corrected TNPH porosity (30-p.u.) line, move parallel
to the closest trend line to intersect the freshwater line.
From that point go straight down to the formation salinity
correction chart at the bottom.
Move parallel to the closest trend line to intersect the
formation salinity line (150,000 ppm), and then draw a
vertical line to the bottom scale to read the corrected
TNPH value (26 p.u.).
Neutron—Wireline
Compensated Neutron Tool
Neu-8
Fluid Σ Correction for Environmentally Corrected TNPH—Open Hole
(former Por-18)
Neutron log porosity index
0
10
20
30
40
50
160
140
Sandstone formation
Fluid Σ (c.u.)
120
100
80
Fresh water
60
250,000-ppm water
40
Neu
20
160
140
Limestone formation
Fluid Σ (c.u.)
120
100
80
Fresh water
60
250,000-ppm water
40
20
160
140
Dolomite formation
Fluid Σ (c.u.)
120
100
80
Fresh water
60
250,000-ppm water
40
20
0
Formation salinity
(1,000 × ppm)
250
0
10
20
30
40
50
© Schlumberger
71
Neutron—Wireline
Compensated Neutron Tool
Environmental Correction—Cased Hole
Purpose
This chart is used to obtain the correct porosity from the neutron
porosity index logged with the compensated neutron tool in casing,
where the effects of the borehole size, casing thickness, and cement
sheath thickness influence the true value of formation porosity.
Neu
Description
Enter the scale at the top of the chart with a whole-number (not
fractional) porosity value. Draw a straight line vertically through
the three charts representing borehole size, casing thickness, and
cement thickness. Draw a horizontal line on each chart from the
appropriate value on the y-axis. At the intersection point of the vertical line and the horizontal line on each chart proceed to the blue
dashed horizontal line by following the slope of the blue solid lines
on each chart. At that point read the change in porosity index. The
cumulative change in porosity is added to the logged porosity to obtain
the corrected value. As can be seen, the major influences to the casingderived porosity are the borehole size and the cement thickness. The
same procedure applies to the metric chart.
The blue dashed lines represent the standard conditions from
which the charts were developed: 8 3⁄4-in. open hole, 51⁄ 2-in. 17-lbm
casing, and 1.62-in. annular cement thickness.
The neutron porosity equivalence nomographs at the bottom are
used to convert from the log standard of limestone porosity to porosity for other matrix materials.
The porosity value corrected with Chart Neu-9 is entered into
Chart Neu-1 to provide environmental corrections necessary for
determining the correct cased hole porosity value.
72
Example
Given:
Find:
Answer:
Log porosity index = 27%, borehole diameter = 11 in.,
casing thickness = 0.304 in., and cement thickness =
1.62 in.
Cement thickness is defined as the annular space
between the outside wall of the casing and the borehole
wall. The value is determined by subtracting the casing
outside diameter from the borehole diameter and dividing by 2.
Porosity corrected for borehole size, casing thickness,
and cement thickness.
Draw a vertical line (shown in red) though the three
charts at 27 p.u.
Borehole-diameter correction chart: From the intersection of the vertical line and the 11-in. borehole-diameter
line (shown in red dashes) move upward along the
curved blue line as shown on the chart.
The porosity is reduced to 26% by –1 p.u.
Casing thickness chart: The porosity index is changed
by 0.3 p.u.
Cement thickness chart: The porosity index is changed
by 0.5 p.u.
The resulting corrected porosity for borehole, casing,
and cement is 27 – 1 + 0.3 + 0.5 = 26.8 p.u.
Neutron—Wireline
Compensated Neutron Tool
Neu-9
Environmental Correction—Cased Hole
(former Por-14a)
Customary
Neutron log porosity index
(p.u.)
Diameter of borehole
before running casing
(in.)
Casing thickness (in.)
9.5
11.6
13.5
Casing
15.1
weight
(lbm/ft)
14
17
20
23
41⁄ 2
20
26
32
51⁄ 2 7
OD (in.)
0
0.3
40
0.4
95⁄8
Cement thickness
(in.)
20
4
6
8 3
10 8 ⁄4 in.
12
14
16
0.2
29
47
10
30
40
50
•
–1.0
•
0.304 in.
0.5
+0.3
0
Neu
1
•
2 1.62 in.
3
+0.5
Borehole, casing, and cement correction = –1.0 + 0.3 + 0.5
Metric
Neutron log porosity index
(p.u.)
100
0
10
20
30
40
50
Diameter of borehole
before running casing
(mm)
200
222 mm
•
Casing thickness (mm)
400
5
7
7.7 mm
9
11
13
•
Casing
weight
(kg/m)
14
17
20
23
114
21.0
25.5
30.0
34.5
30
39
48
43
60
70
140 178 245
OD (mm)
Cement thickness
(mm)
300
0
25
•
50 41 mm
75
0
10
0
10
20
30
40
50
40
50
Neutron porosity equivalence
Calcite (limestone)
Quartz sandstone
Dolomite
© Schlumberger
0
10
0
20
20
30
30
10
40
20
50
30
• Standard conditions
73
Neutron—Wireline
APS* Accelerator Porosity Sonde
Environmental Correction—Open Hole
Purpose
The Neu-10 charts pair is used to correct the APS Accelerator Porosity
Sonde apparent limestone porosity for mud weight and actual bore­
hole size. The charts are for the near-to-array and near-to-far poros­
ity measurements. The design of the APS sonde resulted in a
significant reduction in environmental correction. The answer determined with this chart is used in conjunction with the correction
from Chart Neu-11.
Neu
Description
Enter the appropriate chart pair (mud weight and actual borehole
size) for the APS near-to-array apparent limestone porosity (APLU)
or APS near-to-far apparent limestone porosity (FPLU) with the
uncorrected porosity from the APS log by drawing a straight vertical
line (shown in red) through both of the charts. At the intersection
with the mud weight value, move parallel to the closest trend line to
intersect the standard conditions line. This point represents a change
in porosity resulting from the correction for mud weight. Follow the
same procedure for the borehole size chart to determine that correction change. Because the borehole size correction has a dependency
on mud weight, even with natural muds, there are two sets of curves
on the borehole size chart—solid for light muds (8.345 lbm/gal) and
dashed for heavy muds (16 lbm/gal). Intermediate mud weights are
interpolated. The two differences are summed for the total correction to the APS log value.
This answer is used in Chart Neu-11 to complete the environmental corrections for corrected APLU or FPLU porosity.
74
Example
Given:
Find:
Answer:
APS neutron APLU uncorrected porosity = 34 p.u.,
mud weight = 10 lbm/gal, and borehole size = 12 in.
Corrected APLU porosity.
Draw a vertical line on the APLU mud weight chart from
34 p.u. on the scale above. At the intersection with the
10-lbm/gal mud weight line, move parallel to the trend
line to intersect the standard conditions line. This point
represents a change in porosity of –0.75 p.u.
On the actual borehole size chart, move parallel to the
closest trend line from the intersection of the 34-p.u.
line and the actual borehole size (12 in.) to intersect
the 8-in. standard conditions line. This point represents
a change in porosity of –1.0 p.u.
The total correction is –0.75 + –1.0 = –1.75 p.u.,
which results in a corrected APLU porosity of
34 – 1.75 = 32.25 p.u.
Neutron—Wireline
APS* Accelerator Porosity Sonde
Neu-10
Environmental Correction—Open Hole
(former Por-23a)
APS near-to-array apparent limestone porosity uncorrected, APLU (p.u.)
0
Mud weight
(lbm/gal)
Actual
borehole size
(in.)
10
20
30
40
50
18
16
14
12
10
8
16
14
12
10
8
6
2.0
1.8
1.6
1.4
1.2
1.0
400
350
300
250
200
(g/cm3)
•
Neu
(mm)
•
APS near-to-far apparent limestone porosity uncorrected, FPLU (p.u.)
Mud weight
(lbm/gal)
Actual
borehole size
(in.)
18
16
14
12
10
8
16
14
12
10
8
6
2.0
1.8
1.6
1.4
1.2
1.0
400
350
300
250
200
0
10
20
30
40
(g/cm3)
•
(mm)
•
50
• Standard conditions
*Mark of Schlumberger
© Schlumberger
75
Neutron—Wireline
APS* Accelerator Porosity Sonde Without Environmental Corrections
Neu-11
Environmental Correction—Open Hole
(former Por-23b)
12
Pressure
(psi)
0
2,500
5,000
7,500
10,000
12,500
15,000
17,500
20,000
11
(MPa)
0
10
34
9
69
8
103
7
6
138
5
4
Apparent
porosity
correction
(p.u.)
3
Neu
2
1
(°F)
(°C)
50
10
100
38
150 200 250 300
66
93
121 149
Formation temperature
350
177
50
150
250
Formation salinity
(ppt or g/kg)
50
30
10 0
Formation porosity
(p.u.)
0
–1
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to complete the environmental correction for
APLU and FPLU porosities from the APS log.
Description
Enter the left-hand chart on the x-axis with the temperature of the
formation of interest. Move vertically to intersect the appropriate
formation pressure line. From that point, move horizontally right to
intersect the left edge of the formation salinity chart. Move parallel
to the trend lines to intersect the formation salinity value. From that
point move horizontally to intersect the left edge of the formation
porosity chart. Move parallel to the trend lines to intersect the
uncorrected APLU or FPLU porosity. At that intersection, move
horizontally right to read the apparent porosity correction.
76
Example
Given:
APLU or FPLU porosity = 34 p.u., formation temperature = 150°F, formation pressure = 5,000 psi, and formation salinity = 150,000 ppm.
Find:
Environmentally corrected APLU or FPLU porosity.
Answer:
Enter the formation temperature chart at 150°F to intersect the 5,000-psi curve. From that point move horizontally right to intersect the left edge of the formation
salinity chart. Move parallel to the trend lines to intersect the formation temperature of 150°F. At this point,
again move horizontally to the left edge of the next
chart. Move parallel to the trend lines to intersect the
34-p.u. porosity line. At that point on the y-axis, the
change in porosity is +1.6 p.u.
The total correction for a corrected APLU or FPLU
from Charts Neu-10 and Neu-11 is
34 + (–0.75 + –1) + 1.6 = 33.85 p.u.
Neutron—LWD
CDN* Compensated Density Neutron, adnVISION* Azimuthal Density
Neutron, and EcoScope* Integrated LWD Tools
Mud Hydrogen Index Determination
Purpose
This chart is used to determine one of several environmental
corrections for neutron porosity values recorded with the CDN
Compensated Density Neutron, adnVISION Azimuthal Density
Neutron, and EcoScope Integrated LWD tools. The value of hydrogen
index (Hm) is used in the following porosity correction charts.
Description
To determine the Hm of the drilling mud, the mud weight, temperature, and hydrostatic mud pressure at the zone of interest must
be known.
Example
Given:
Find:
Answer:
Barite mud weight = 14 lbm/gal, mud temperature = 150°F,
and hydrostatic mud pressure = 5,000 psi.
Hydrogen index of the drilling mud.
Enter the bottom chart for mud weight at 14 lbm/gal on
the y-axis. Move horizontally to intersect the barite line.
Move vertically to the bottom of the mud temperature
chart and move upward parallel to the closest trend line
to intersect the formation temperature. From the intersection point move vertically to the bottom of the mud
pressure chart.
Move parallel to the closest trend line to intersect the
formation pressure. Draw a line vertically to intersect
the mud hydrogen index scale and read the result.
Mud hydrogen index = 0.78.
continued on next page
77
Neu
Neutron—LWD
CDN* Compensated Density Neutron, adnVISION* Azimuthal Density Neutron, and
EcoScope* Integrated LWD Tools
Mud Hydrogen Index Determination
Mud hydrogen index, Hm
0.70
0.75
0.80
0.85
0.90
0.95
1
0.95
1
25
20
Mud
pressure
(1,000 × psi)
Neu
10
0
300
Mud
temperature
(°F)
200
100
50
16
14
Mud
weight
(lbm/gal)
Barite
12
10
Bentonite
8
0.70
*Mark of Schlumberger
© Schlumberger
78
0.75
0.80
0.85
0.90
Neu-30
(former Por-19)
Neutron—LWD
adnVISION475* Azimuthal Density Neutron—4.75-in. Tool and 6-in. Borehole
Environmental Correction—Open Hole
Purpose
This is one of a series of charts used to correct adnVISION475
4.75-in. Azimuthal Density Neutron tool porosity for several environmental effects by using the mud hydrogen index (Hm) determined
from Chart Neu-30 in conjunction with the parameters on the chart.
Example
Given:
Description
This chart incorporates the parameters of borehole size, mud temperature, mud hydrogen index (from Chart Neu-30), mud salinity,
and formation salinity for the correction of adnVISION475 porosity.
The following charts are used with the same interpretation
procedure as Chart Neu-31. The charts differ for tool size and
borehole size.
Find:
Answer:
adnVISION475 uncorrected porosity = 34 p.u., borehole
size = 10 in., mud temperature = 150°F, hydrogen
index = 0.78, borehole salinity = 100,000 ppm, and formation salinity = 100,000 ppm.
Corrected adnVISION475 porosity.
From the adnVISION475 porosity of 34 p.u. on the top
scale, enter the borehole size chart to intersect the borehole size of 10 in. From the point of intersection move
parallel to the closest trend line to intersect the standard conditions line.
From this intersection point move straight down to
enter the mud temperature chart and intersect the mud
temperature of 150°F. From the point of intersection
move parallel to the closest trend line to intersect the
standard conditions line.
Continue this pattern through the charts to read the
corrected porosity from the scale at the bottom of the
charts.
The corrected adnVISION475 porosity is 17 p.u.
continued on next page
79
Neu
Neutron—LWD
adnVISION475* Azimuthal Density Neutron—4.75-in. Tool and 6-in. Borehole
Neu-31
Environmental Correction—Open Hole
adnVISION475 neutron porosity index (apparent limestone porosity) in 6-in. borehole
0
10
20
30
40
50
10
Borehole
size
(in.)
8
•
6
300
Mud
temperature
(°F)
Neu
200
100
•
0.7
Mud
hydrogen
index, Hm
0.8
0.9
•
1.0
Mud
salinity
(1,000 × ppm)
200
100
•
0
200
Formation
salinity
(1,000 × ppm)
100
•
0
0
10
20
30
40
50
• Standard conditions
*Mark of Schlumberger
© Schlumberger
80
Neutron—LWD
adnVISION475* BIP Neutron—4.75-in. Tool and 6-in. Borehole
Neu-32
Environmental Correction—Open Hole
adnVISION475 neutron porosity index (apparent limestone porosity) in 6-in. borehole
0
10
20
30
40
50
300
Mud
temperature
(°F)
200
100
Neu
0.7
Mud
hydrogen
index, Hm
0.8
0.9
1.0
Mud
salinity
(1,000 × ppm)
200
100
0
Formation
salinity
(1,000 × ppm)
200
100
0
0
10
20
30
40
50
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Neu-31 to correct
adnVISION475 borehole-invariant porosity (BIP) measurements.
Description
Enter the top scale with the BIP neutron porosity (BNPH) to incorporate corrections for mud temperature, mud hydrogen index, and
mud and formation salinity.
81
Neutron—LWD
adnVISION475* Azimuthal Density Neutron—4.75-in. Tool
and 8-in. Borehole
Neu-33
Environmental Correction—Open Hole
adnVISION475 neutron porosity index (apparent limestone porosity) in 8-in. borehole
0
10
20
30
40
50
10
Borehole
size
(in.)
8
•
6
300
Mud
temperature
(°F)
Neu
200
100
•
0.7
Mud
hydrogen
index, Hm
0.8
0.9
•
1.0
Mud
salinity
(1,000 × ppm)
200
100
•
0
200
Formation
salinity
(1,000 × ppm)
100
•
0
0
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Neu-31 to correct
adnVISION475 porosity.
82
10
20
30
40
50
• Standard conditions
Neutron—LWD
adnVISION475* BIP Neutron—4.75-in. Tool and 8-in. Borehole
Neu-34
Environmental Correction—Open Hole
adnVISION475 neutron porosity index (apparent limestone porosity) in 8-in. borehole
0
10
20
30
40
50
300
Mud
temperature
(°F)
200
100
0.7
Mud
hydrogen
index, Hm
0.8
Neu
0.9
1.0
Mud
salinity
(1,000 × ppm)
200
100
0
Formation
salinity
(1,000 × ppm)
200
100
0
*Mark of Schlumberger
© Schlumberger
0
10
20
30
40
50
Purpose
This chart is used similarly to Chart Neu-32 to correct
adnVISION475 borehole-invariant porosity (BIP) measurements.
83
Neutron—LWD
adnVISION675* Azimuthal Density Neutron—6.75-in. Tool and 8-in. Borehole
Neu-35
Environmental Correction—Open Hole
(former Por-26a)
adnVISION675 neutron porosity index (apparent limestone porosity in p.u.)
0
10
20
30
40
50
16
Borehole
size
(in.)
14
12
10
8
•
300
Neu
Mud
temperature
(°F)
200
100
50
•
0.7
Mud
hydrogen
index, Hm
0.8
0.9
1.0
•
250
200
Mud
salinity
(1,000 × ppm)
100
0
•
250
200
Formation
salinity
(1,000 × ppm)
100
0
•
0
10
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Neu-31 to correct adnVISION675
porosity.
84
20
30
40
50
• Standard conditions
Neutron—LWD
adnVISION675* BIP Neutron—6.75-in. Tool and 8-in. Borehole
Neu-34
Environmental Correction—Open Hole
adnVISION475 neutron porosity index (apparent limestone porosity) in 8-in. borehole
0
10
20
30
40
50
300
Mud
temperature
(°F)
200
100
0.7
Mud
hydrogen
index, Hm
0.8
0.9
Neu
1.0
Mud
salinity
(1,000 × ppm)
200
100
0
Formation
salinity
(1,000 × ppm)
200
100
0
0
10
20
30
40
50
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Neu-32 to correct
adnVISION675 borehole-invariant porosity (BIP) measurements.
85
Neutron—LWD
adnVISION675* Azimuthal Density Neutron—6.75-in. Tool and 10-in. Borehole
Neu-37
Environmental Correction—Open Hole
(former Por-26b)
adnVISION675 neutron porosity index (apparent limestone porosity in p.u.)
0
10
20
30
40
50
16
Borehole
size
(in.)
14
12
10
8
•
300
Neu
Mud
temperature
(°F)
200
100
50
•
0.7
Mud
hydrogen
index, Hm
0.8
0.9
1.0
•
250
200
Mud
salinity
(1,000 × ppm)
100
0
•
250
200
Formation
salinity
(1,000 × ppm)
100
0
•
0
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Neu-31 to correct
adnVISION675 porosity.
86
10
20
30
40
50
• Standard conditions
Neutron—LWD
adnVISION675* BIP Neutron—6.75-in. Tool and 10-in. Borehole
Neu-38
Environmental Correction—Open Hole
adnVISION675 neutron porosity index (apparent limestone porosity) in 10-in. borehole
0
10
20
30
40
50
300
Mud
temperature
(°F)
200
100
0.7
Mud
hydrogen
index, Hm
0.8
Neu
0.9
1.0
Mud
salinity
(1,000 × ppm)
200
100
0
Formation
salinity
(1,000 × ppm)
200
100
0
*Mark of Schlumberger
© Schlumberger
0
10
20
30
40
50
Purpose
This chart is used similarly to Chart Neu-32 to correct
adnVISION675 borehole-invariant porosity (BIP) measurements.
87
Neutron—LWD
adnVISION825* Azimuthal Density Neutron—8.25-in. Tool
and 12.25-in. Borehole
Neu-39
Environmental Correction—Open Hole
Standoff = 0.25 in.
adnVISION825 neutron porosity index (apparent limestone porosity) in 12.25-in. borehole
0
10
20
30
40
50
1.5
Standoff
(in.)
1.0
0.5
•
0
16
Borehole
size
(°F)
Neu
14
•
12
10
300
Mud
temperature
(°F)
200
100
•
0.7
Mud
hydrogen
index, Hm
0.8
0.9
•
1
20
Pressure
(1,000 × psi)
10
•
0
Mud
salinity
(1,000 × ppm)
Formation
salinity
(1,000 × ppm)
200
100
0
•
200
100
•
0
0
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Neu-31 to correct
adnVISION825 porosity.
88
10
20
30
40
50
• Standard conditions
Neutron—LWD
CDN* Compensated Density Neutron and adnVISION825s*
Azimuthal Density Neutron—8-in. Tool and 12-in. Borehole
Neu-40
(former Por-24c)
Environmental Correction—Open Hole
Neutron porosity index (apparent limestone porosity) in 12-in. borehole
0
10
20
30
40
50
18
Borehole
size
(in.)
16
14
•
12
350
300
Mud
temperature
(°F)
Neu
200
100
50
•
0.7
Mud
hydrogen
index, Hm
0.8
0.9
1.0
•
250
200
Mud
salinity
(1,000 × ppm)
100
•
0
250
200
Formation
salinity
(1,000 × ppm)
100
•
0
0
10
*Mark of Schlumberger
© Schlumberger
20
30
40
50
• Standard conditions
Purpose
This chart is used similarly to Chart Neu-31 to correct
CDN Compensated Density Neutron tool and adnVISION825s
Azimuthal Density Neutron porosity.
89
Neutron—LWD
CDN* Compensated Density Neutron and adnVISION825s*
Azimuthal Density Neutron—8-in. Tool and 14-in. Borehole
Neu-41
(former Por-24d)
Environmental Correction—Open Hole
Neutron porosity index (apparent limestone porosity) in 14-in. borehole
0
10
20
30
40
A
18
Borehole
size
(in.)
50
16
B
14
12
•
C
350
Neu
300
Mud
temperature
(°F)
200
D
100
50
•
E
0.7
Mud
hydrogen
index, Hm
F
0.8
0.9
1.0
•
G
250
200
Mud
salinity
(1,000 × ppm)
H
100
I
0
•
250
200
Formation
salinity
(1,000 × ppm)
100
J
0
0
*Mark of Schlumberger
© Schlumberger
90
•
K
10
20
30
40
50
• Standard conditions
Neutron—LWD
CDN* Compensated Density Neutron and adnVISION825s*
Azimuthal Density Neutron—8-in. Tool and 16-in. Borehole
Neu-42
(former Por-24e)
Environmental Correction—Open Hole
Neutron porosity index (apparent limestone porosity) in 16-in. borehole
0
10
20
30
40
50
18
Borehole
size
(in.)
16
14
12
•
350
Neu
300
Mud
temperature
(°F)
200
100
•
50
0.7
Mud
hydrogen
index, Hm
0.8
0.9
1.0
•
250
200
Mud
salinity
(1,000 × ppm)
100
0
•
250
200
Formation
salinity
(1,000 × ppm)
100
0
•
0
*Mark of Schlumberger
© Schlumberger
10
20
30
40
50
• Standard conditions
91
Neutron—LWD
EcoScope* Integrated LWD Neutron Porosity—6.75-in. Tool
Environmental Correction—Open Hole
Purpose
Charts Neu-43 through Neu-46 show the environmental corrections
that are applied to EcoScope 6.75-in. Integrated LWD Tool neutron
porosity measurements. These charts can be used to estimate the
correction that is normally already applied to the field logs.
Description
The charts incorporate the parameters of borehole size, mud temperature, mud hydrogen index (from Chart Neu-30), mud salinity,
and formation salinity for the correction of EcoScope 6.75-in.
neutron porosity.
Select the appropriate chart based on both the hole size and
the measurement type: thermal neutron porosity (TNPH) or best
thermal neutron porosity (BPHI).
Neu
92
Enter the charts with the uncorrected neutron porosity data.
Charts Neu-43 and Neu-44 are for use with BPHI_UNC, and Charts
Neu-45 and Neu-46 are for use with TNPH_UNC. Because the borehole size correction is applied to the field logs, including the _UNC
channels, do not include the borehole size correction, which is in the
charts for illustrative purposes only.
A correction for eccentricity effects is normally also applied to
the field BPHI measurement. Because this correction is not included
in these charts, there may be a small difference between the correction estimated from the charts and that actually applied to the field
data, depending on the tool position in the borehole.
The charts are used with a similar procedure to that described for
Chart Neu-31.
Neutron—LWD
EcoScope* Integrated LWD BPHI Porosity—6.75-in. Tool and 8.5-in. Borehole
Environmental Correction—Open Hole
Neu-43
EcoScope uncorrected BPHI porosity (apparent limestone porosity in p.u.) in 8.5-in. borehole
0
10
20
30
40
50
14
13
Borehole
size
(in.)
12
11
10
9
8
•
260
210
Temperature
(°F)
Neu
160
110
60
•
0.70
0.75
Mud
hydrogen
index, Hm
0.80
0.85
0.90
0.95
1.00
•
250
200
150
Mud
salinity
100
(1,000 × ppm)
50
0
•
250
200
150
Formation
salinity
100
(1,000 × ppm)
50
0
•
0
10
20
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Neu-31 to estimate the correction applied to EcoScope 6.75-in. Integrated LWD Tool best thermal
neutron porosity (BPHI) measurements.
30
40
50
• Standard conditions
Use this chart only with EcoScope BPHI neutron porosity; use
Chart Neu-45 with EcoScope thermal neutron porosity (TNPH)
measurements.
93
Neutron—LWD
EcoScope* Integrated LWD BPHI Porosity—6.75-in. Tool and 9.5-in. Borehole
Environmental Correction—Open Hole
Neu-44
EcoScope uncorrected BPHI porosity (apparent limestone porosity in p.u.) in 9.5-in. borehole
0
10
20
30
40
50
14
13
Borehole
size
(in.)
12
11
10
9
8
•
260
210
Neu
Temperature
(°F)
160
110
60
•
0.70
0.75
Mud
hydrogen
index, Hm
0.80
0.85
0.90
0.95
1.00
•
250
200
150
Mud
salinity
100
(1,000 × ppm)
50
0
•
250
200
150
Formation
salinity
100
(1,000 × ppm)
50
0
•
0
10
20
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Neu-31 to estimate the correction applied to EcoScope 6.75-in. Integrated LWD Tool best thermal
neutron porosity (BPHI) measurements.
94
30
40
50
• Standard conditions
Use this chart only with EcoScope BPHI neutron porosity; use
Chart Neu-46 with EcoScope thermal neutron porosity (TNPH)
measurements.
Neutron—LWD
EcoScope* Integrated LWD TNPH Porosity—6.75-in. Tool and 8.5-in. Borehole
Environmental Correction—Open Hole
Neu-45
EcoScope uncorrected TNPH porosity (apparent limestone porosity in p.u.) in 8.5-in. borehole
0
10
20
30
40
50
14
13
Borehole
size
(in.)
12
11
10
9
8
•
260
210
Temperature
(°F)
Neu
160
110
60
•
0.70
0.75
Mud
hydrogen
index, Hm
0.80
0.85
0.90
0.95
1.00
•
250
200
150
Mud
salinity
100
(1,000 × ppm)
50
0
•
250
200
150
Formation
salinity
100
(1,000 × ppm)
50
0
•
0
10
20
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Neu-31 to estimate the correction applied to EcoScope 6.75-in. Integrated LWD Tool thermal neutron porosity (TNPH) measurements.
30
40
50
• Standard conditions
Use this chart only with EcoScope TNPH measurements. Use
Chart Neu-43 with EcoScope best thermal neutron porosity (BPHI)
measurements.
95
Neutron—LWD
EcoScope* Integrated LWD TNPH Porosity—6.75-in. Tool and 9.5-in. Borehole
Environmental Correction—Open Hole
Neu-46
EcoScope uncorrected TNPH porosity (apparent limestone porosity in p.u.) in 9.5-in. borehole
0
10
20
30
40
50
14
13
Borehole
size
(in.)
12
11
10
9
8
•
260
210
Neu
Temperature
(°F)
160
110
60
•
0.70
0.75
Mud
hydrogen
index, Hm
0.80
0.85
0.90
0.95
1.00
•
250
200
150
Mud
salinity
100
(1,000 × ppm)
50
0
•
250
200
150
Formation
salinity
100
(1,000 × ppm)
50
0
•
0
10
20
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Neu-31 to estimate the correction applied to EcoScope 6.75-in. Integrated LWD Tool thermal neutron porosity (TNPH) measurements.
96
30
40
50
• Standard conditions
Use this chart only with EcoScope TNPH neutron porosity; use
Chart Neu-44 with EcoScope best thermal neutron porosity (BPHI)
measurements.
Neutron—LWD
EcoScope* Integrated LWD—6.75-in. Tool
Formation Sigma Environmental Correction—Open Hole
Purpose
This chart is used to environmentally correct the raw sigma (RFSA)
measurement for porosity, borehole size, and mud salinity. The fully
corrected sigma (SIFA) measurement is normally presented on the
logs.
Description
Chart Neu-47 includes (from top to bottom) the moments sigma
transform, diffusion correction based on porosity, and borehole
correction.
Example
Given: Raw sigma (24 c.u.), porosity (30 p.u.), borehole size
(10 in.), and mud salinity (200,000 ppm).
Find:
Corrected sigma (SIFA).
Answer: Enter the chart from the scale at the top with the raw sigma value of 24 c.u.
Moments Sigma Transform
Move parallel to the closest trend line to intersect the x-axis of the
moments sigma transform chart. The difference between the x-axis
value and the raw sigma value is the moments sigma transform
correction (19.8 – 24 = –4.2 c.u.).
Diffusion Correction
Move down vertically from the scale at the top to intersect the
30-p.u. line on the porosity chart. At the intersection point, move
parallel to the closest trend line to intersect the x-axis of the
porosity chart.
The difference between the x-axis value and the raw sigma value
is the diffusion correction (25.3 – 24 = +1.3 c.u.).
Borehole Correction
Move down vertically from the scale at the top to intersect the 10-in.
borehole size line. At the intersection point, move parallel to the
closest trend line corresponding to the mud salinity to intersect
the x-axis of the borehole correction chart.
The difference between the x-axis value and the raw sigma value
is the borehole correction (22.8 – 24 = –1.2 c.u.).
Net Correction
The net correction to apply to the raw sigma value is the sum the
three corrections (–4.2 + 1.3 + –1.2 = –4.1 c.u.). The environmentally
corrected sigma is the sum of the net correction and the raw sigma
value (24 + –4.1 = 19.9 c.u.).
EcoScope Sigma Correction Example
Correction
Raw sigma
24 c.u.
Porosity
30 p.u.
Borehole size
10 in.
Mud salinity
200,000 ppm
Moments sigma transform
Porosity correction
Borehole correction
Net correction
Environmentally corrected sigma
–4.2 c.u.
+1.3 c.u.
–1.2 c.u.
–4.1 c.u.
19.9 c.u.
continued on next page
97
Neu
Neutron—LWD
EcoScope* Integrated LWD—6.75-in. Tool
Neu-47
Formation Sigma Environmental Correction—Open Hole
Raw sigma (c.u.)
0
10
20
30
40
50
60
10
20
30
40
50
60
Moments
sigma
transform
50
40
30
Porosity
(p.u.)
Neu
20
10
0
11
10
Borehole
size (in.)
9 Mud salinity
0 ppm
50,000 ppm
100,000 ppm
150,000 ppm
200,000 ppm
8
0
*Mark of Schlumberger
© Schlumberger
98
• Standard conditions
General Magnetic Resonance–—Wireline
Nuclear
CMR* Tool
CMR-1
Hydrocarbon Effect on NMR/Density Porosity Ratio
1.0
ρh = 0.8
0.7
0.8
0.6
0.5
0.6
φtCMR
φD
0.4
0.4
0.3
0.2
0.2
0
0.1
0
0.2
0.4
0.6
NMR
0.8
1.0
1 – Sxo
1.4
Fresh Mud and Dry Gas at 700 psi
Fresh Mud and Dry Gas at 700 psi
ρma = 2.65, ρf = 1, If = 1, ρgas = 0.25,
PT = 4, T1 gas = 4, IH = 0.5
ρma = 2.71, ρf = 1, If = 1, ρgas = 0.25,
PT = 4, T1 gas = 4, Igas = 0.5
0%
20%
1.6
1.4
Porosity = 50 p.u.
1.6
40%
60%
40 p.u.
80%
1.8
Gas
2.0
ρb
(g/cm3) 2.2
30 p.u.
20 p.u.
2.4
*Mark of Schlumberger
© Schlumberger
2.6
*Mark of Schlumberger
© Schlumberger
Porosity = 50 p.u.
40%
40 p.u. 60%
80%
20%
1.8
Sxo = 100%
Water
ρb
(g/cm3)
Gas
2.0
2.2
30 p.u.
Sxo = 100%
20 p.u.
2.4
10 p.u.
10 p.u.
Water
2.6
0
0
0%
0
0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50
0
φtCMR
Purpose
This chart is used to determine the saturation of the flushed zone
(Sxo) and hydrocarbon density (ρh) by using density (ρ) and CMR
Combinable Magnetic Resonance data.
Description
The top chart has three components: ratio of total CMR porosity
to density porosity (ϕtCMR/ϕD) on the y-axis, (1 – Sxo) values on the
x-axis, and ρh defined by the radiating lines from the value of unity
on the y-axis. Enter the chart with the values for (1 – Sxo) and the
ϕtCMR /ϕD ratio. The intersection point indicates the hydrocarbon
0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50
φtCMR
density value. The bottom charts are used to determine the Sxo value
in sandstone (left) and limestone (right).
Example
Given:
Find:
Answer:
CMR porosity = 25 p.u., ϕD = 30 p.u., and Sxo = 80%.
Hydrocarbon density of the fluid in the formation.
ϕtCMR/ϕD ratio = 25/30 = 0.83.
1 – Sxo = 1 – 0.8 = 0.20 or 20%.
For these values, ρh = 0.40.
99
This page intentionally left blank.
Resistivity Laterolog—Wireline
ARI* Azimuthal Resistivity Imager
RLl-1
Environmental Correction—Open Hole
(former Rcor-14)
35⁄8-in. Tool Centered, Active Mode, Thick Beds
1.5
Rt /Ra
6
8
10
12
Hole diameter (in.)
1.0
0.5
1
10
100
1,000
10,000
Ra /Rm
RLl
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to environmentally correct the ARI Azimuthal
Resistivity Imager high-resolution resistivity (LLhr) curve for the
effect of borehole size.
Example
Given:
Description
For a known value of resistivity of the borehole mud (Rm) at the zone
of interest, a correction for the recorded log azimuthal resistivity (Ra)
is determined by using this chart. The resistivity measured by the
ARI tool is equal to or higher than the corrected resistivity (Rt) for
borehole sizes of 8 to 12 in. However, the measured ARI resistivity
is lower than Rt in 6-in. boreholes and for values of Ra / Rm between
6 and 600.
Find:
Answer:
ARI LLhr resistivity (Ra) = 20 ohm-m, mud resistivity
(Rm) = 0.02 ohm-m, and borehole size at the zone of
interest = 10 in.
True resistivity (Rt).
Enter the chart at the x-axis with the ratio Ra /Rm =
20/0.02 = 1,000.
Move vertically upward to intersect the 10-in. line. Move
horizontally left to read the Rt /Ra value on the y-axis
of 0.86.
Multiply the ratio by Ra to obtain the corrected LLhr
resistivity:
Rt = 0.86 × 20 = 17.2 ohm-m.
101
Resistivity Laterolog—Wireline
High-Resolution Azimuthal Laterolog Sonde (HALS)
RLl-2
HLLD Borehole Correction—Open Hole
HLLD Tool Centered (Rm = 0.1 ohm-m)
1.2
dh
5 in.
6 in.
8 in.
10 in.
12 in.
14 in.
16 in.
1.1
1.0
R t /HLLD
0.9
0.8
0.7
0.6
10–1
100
101
102
103
104
105
HLLD/Rm
RLl
1.5
Borehole Effect, HLLD Tool Centered (Rm = 0.1 ohm-m)
dh
6 in.
8 in.
10 in.
12 in.
14 in.
16 in.
18 in.
20 in.
1.3
1.1
R t /HLLD
0.9
0.7
0.5
100
101
102
103
104
105
HLLD/Rm
© Schlumberger
Purpose
This chart is used to correct the HALS laterolog deep resistivity
(HLLD) for borehole and drilling mud effects.
Description
Enter the chart on the x-axis with the value of HLLD divided by
the mud resistivity (Rm) at formation temperature. Move upward
to intersect the curve representing the borehole diameter (dh), and
then move horizontally left to read the value of the ratio Rt /HLLD on
the y-axis. Multiply this value by the HLLD value to obtain Rt. Charts
102
RLl-3 through RLl-14 are similar to Chart RLl-2 for different resistivity
measurements and values of tool standoff.
Example
Given:
Find:
Answer:
HLLD = 100 ohm-m, Rm = 0.02 ohm-m at formation
temperature, and borehole size = 10 in.
Rt.
Ratio of HLLD/Rm = 100/0.02 = 5,000.
Rt = 0.80 × 100 = 80 ohm-m.
Resistivity Laterolog—Wireline
High-Resolution Azimuthal Laterolog Sonde (HALS)
RLl-3
HLLS Borehole Correction—Open Hole
HLLS Tool Centered (Rm = 0.1 ohm-m)
3.0
dh
5 in.
6 in.
8 in.
10 in.
12 in.
14 in.
16 in.
2.5
2.0
R t / HLLS
1.5
1.0
0.5
0
10–1
100
101
102
103
104
105
HLLS/Rm
RLl
Borehole Effect, HLLS Tool Centered (Rm = 0.1 ohm-m)
3.0
dh
6 in.
8 in.
10 in.
12 in.
14 in.
16 in.
18 in.
20 in.
2.5
2.0
R t /HLLS
1.5
1.0
0.5
0
10 0
101
102
103
104
105
HLLS/Rm
© Schlumberger
Purpose
This chart is used similarly to Chart RLl-2 to correct HALS laterolog
shallow resistivity (HLLS) for borehole and drilling mud effects.
103
Resistivity Laterolog—Wireline
High-Resolution Azimuthal Laterolog Sonde (HALS)
RLl-4
HRLD Borehole Correction—Open Hole
1.1
1.0
0.9
0.8
R t /HRLD
HRLD Tool Centered (R m = 0.1 ohm-m)
dh
5 in.
6 in.
8 in.
10 in.
12 in.
14 in.
16 in.
0.7
0.6
0.5
0.4
10–1
100
101
102
103
104
105
HRLD/Rm
RLl
1.4
Borehole Effect, HRLD Tool Centered (Rm = 0.1 ohm-m)
dh
6 in.
8 in.
10 in.
12 in.
14 in.
16 in.
18 in.
20 in.
1.2
1.0
Rt /HRLD
0.8
0.6
0.4
10 0
101
102
103
HRLD/Rm
© Schlumberger
Purpose
This chart is used to similarly to Chart RLl-2 to correct the HALS
high-resolution deep resistivity (HRLD) for borehole and drilling
mud effects.
104
104
105
Resistivity Laterolog—Wireline
High-Resolution Azimuthal Laterolog Sonde (HALS)
RLl-5
HRLS Borehole Correction—Open Hole
HRLS Tool Centered (Rm = 0.1 ohm-m)
3.0
2.5
2.0
R t /HRLS 1.5
dh
5 in.
6 in.
8 in.
10 in.
12 in.
14 in.
16 in.
1.0
0.5
0
10–1
100
101
102
103
104
105
HRLS/Rm
RLl
Borehole Effect, HRLS Tool Centered (Rm = 0.1 ohm-m)
3.0
2.5
2.0
Rt /HRLS
1.5
dh
6 in.
8 in.
10 in.
12 in.
14 in.
16 in.
18 in.
20 in.
1.0
0.5
0
10 0
101
102
103
104
105
HRLS/Rm
© Schlumberger
Purpose
This chart is used to similarly to Chart RLl-2 to correct the HALS
high-resolution shallow resistivity (HRLS) for borehole and drilling
mud effects.
105
Resistivity Laterolog—Wireline
High-Resolution Azimuthal Laterolog Sonde (HALS)
RLl-6
HLLD Borehole Correction—Eccentered in Open Hole
HLLD Tool Eccentered at Standoff = 0.5 in. (Rm = 0.1 ohm-m)
1.2
dh
5 in.
6 in.
8 in.
10 in.
12 in.
14 in.
16 in.
1.1
1.0
Rt /HLLD
0.9
0.8
0.7
0.6
10–1
100
101
102
103
104
105
HLLD/Rm
RLl
HLLD Tool Eccentered at Standoff = 1.5 in. (Rm = 0.1 ohm-m)
1.2
dh
8 in.
10 in.
12 in.
14 in.
16 in.
1.1
1.0
Rt /HLLD
0.9
0.8
0.7
0.6
10–1
100
101
102
HLLD/Rm
© Schlumberger
Purpose
This chart is used to similarly to Chart RLl-2 to correct the HALS
laterolog deep resistivity (HLLD) for borehole and drilling mud effects
at 0.5- and 1.5-in. standoffs.
106
103
104
105
Resistivity Laterolog—Wireline
High-Resolution Azimuthal Laterolog Sonde (HALS)
RLl-7
HLLS Borehole Correction—Eccentered in Open Hole
HLLS Tool Eccentered at Standoff = 0.5 in. (Rm = 0.1 ohm-m)
3.0
dh
5 in.
6 in.
8 in.
10 in.
12 in.
14 in.
16 in.
2.5
2.0
Rt /HLLS
1.5
1.0
0.5
0
10–1
100
101
102
103
104
105
HLLS/Rm
RLl
HLLS Tool Eccentered at Standoff = 1.5 in. (Rm = 0.1 ohm-m)
3.0
dh
8 in.
10 in.
12 in.
14 in.
16 in.
2.5
2.0
Rt /HLLS
1.5
1.0
0.5
0
10–1
100
101
102
103
104
105
HLLS/Rm
© Schlumberger
Purpose
This chart is used to similarly to Chart RLl-2 to correct the HALS
laterolog shallow resistivity (HLLS) for borehole and drilling
mud effects at 0.5- and 1.5-in. standoffs.
107
Resistivity Laterolog—Wireline
High-Resolution Azimuthal Laterolog Sonde (HALS)
RLl-8
HRLD Borehole Correction—Eccentered in Open Hole
1.1
1.0
0.9
0.8
Rt /HRLD
HRLD Tool Eccentered at Standoff = 0.5 in. (Rm = 0.1 ohm-m)
dh
5 in.
6 in.
8 in.
10 in.
12 in.
14 in.
16 in.
0.7
0.6
0.5
0.4
10–1
100
101
102
103
104
105
HRLD/Rm
RLl
HRLD Tool Eccentered at Standoff = 1.5 in. (Rm = 0.1 ohm-m)
1.1
1.0
0.9
Rt /HRLD
dh
8 in.
10 in.
12 in.
14 in.
16 in.
0.8
0.7
0.6
0.5
0.4
10–1
100
101
102
HRLD/Rm
© Schlumberger
Purpose
This chart is used to similarly to Chart RLl-2 to correct the HALS
high-resolution deep resistivity (HRLD) for borehole and drilling
mud effects at 0.5- and 1.5-in. standoffs.
108
103
104
105
Resistivity Laterolog—Wireline
High-Resolution Azimuthal Laterolog Sonde (HALS)
RLl-9
HRLS Borehole Correction—Eccentered in Open Hole
3.0
2.5
2.0
Rt /HRLS
1.5
HRLS Tool Eccentered Standoff = 0.5 in. (Rm = 0.1 ohm-m)
dh
5 in.
6 in.
8 in.
10 in.
12 in.
14 in.
16 in.
1.0
0.5
0
10–1
100
10 1
102
103
104
105
HRLS/Rm
RLl
HRLS Tool Eccentered Standoff = 1.5 in. (Rm = 0.1 ohm-m)
3.0
2.5
2.0
Rt /HRLS
dh
8 in.
10 in.
12 in.
14 in.
16 in.
1.5
1.0
0.5
0
10–1
100
101
102
103
104
105
HRLS/Rm
© Schlumberger
Purpose
This chart is used to similarly to Chart RLl-2 to correct the HALS
high-resolution shallow resistivity (HRLS) for borehole and drilling
mud effects at 0.5- and 1.5-in. standoffs.
109
Resistivity Laterolog—Wireline
HRLA* High-Resolution Laterolog Array
RLl-10
Borehole Correction—Open Hole
Tool Centered
3.0
2.5
2.0
Rt /RLA1
1.5
1.0
0.5
0
10 –1
10 0
101
103
10 2
10 4
10 5
10 6
10 4
10 5
10 6
RLA1/Rm
Standoff = 0.5 in.
3.0
2.5
RLl
2.0
Rt /RLA1
1.5
1.0
0.5
0
10 –1
100
101
10 3
10 2
RLA1/Rm
Standoff = 1.5 in.
3.0
dh
5 in.
6 in.
8 in.
9 in.
10 in.
12 in.
14 in.
16 in.
18 in.
20 in.
22 in.
2.5
2.0
Rt /RLA1
1.5
1.0
0.5
0
10 –1
100
101
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to similarly to Chart RLl-2 to correct HRLA HighResolution Laterolog Array resistivity for borehole and drilling mud
110
10 3
10 2
10 4
10 5
10 6
RLA1/Rm
effects. RLA1 is the apparent resistivity from computed focusing
mode 1.
Resistivity Laterolog—Wireline
General
HRLA* High-Resolution Laterolog Array
RLl-11
Borehole Correction—Open Hole
Tool Centered
3.0
2.5
2.0
Rt /RLA2
1.5
1.0
0.5
0
10 –1
100
101
102
103
104
105
106
RLA2/Rm
Standoff = 0.5 in.
3.0
dh
5 in.
6 in.
8 in.
9 in.
10 in.
12 in.
14 in.
16 in.
18 in.
20 in.
22 in.
2.5
2.0
Rt /RLA2
1.5
1.0
0.5
0
10 –1
100
101
102
103
104
105
106
104
105
106
RLl
RLA2/Rm
Standoff = 1.5 in.
3.0
2.5
2.0
Rt /RLA2
1.5
1.0
0.5
0
10 –1
*Mark of Schlumberger
© Schlumberger
100
101
102
103
RLA2/Rm
Purpose
This chart is used to similarly to Chart RLl-2 to correct HRLA HighResolution Laterolog Array resistivity for borehole and drilling mud
effects. RLA2 is the apparent resistivity from computed focusing
mode 2.
111
Resistivity Laterolog—Wireline
HRLA* High-Resolution Laterolog Array
RLl-12
Borehole Correction—Open Hole
Tool Centered
3.0
2.5
2.0
Rt /RLA3
1.5
1.0
0.5
0
10 –1
100
101
102
103
104
105
106
RLA3/Rm
Standoff = 0.5 in.
3.0
dh
5 in.
6 in.
8 in.
9 in.
10 in.
12 in.
14 in.
16 in.
18 in.
20 in.
22 in.
2.5
RLl
2.0
Rt /RLA3
1.5
1.0
0.5
0
10 –1
100
101
102
103
104
105
106
104
105
106
RLA3/Rm
Standoff = 1.5 in.
3.0
2.5
2.0
Rt /RLA3
1.5
1.0
0.5
0
10 –1
*Mark of Schlumberger
© Schlumberger
100
101
102
103
RLA3/Rm
Purpose
This chart is used to similarly to Chart RLl-2 to correct HRLA HighResolution Laterolog Array resistivity for borehole and drilling mud
112
effects. RLA3 is the apparent resistivity from computed focusing
mode 3.
Resistivity Laterolog—Wireline
HRLA* High-Resolution Laterolog Array
RLl-13
Borehole Correction—Open Hole
Tool Centered
3.0
2.5
2.0
Rt /RLA4
1.5
1.0
0.5
0
10 –1
100
101
102
103
104
105
106
RLA4/Rm
Standoff = 0.5 in.
3.0
dh
5 in.
6 in.
8 in.
9 in.
10 in.
12 in.
14 in.
16 in.
18 in.
20 in.
22 in.
2.5
2.0
Rt /RLA4
1.5
1.0
0.5
0
10 –1
100
101
102
103
104
105
106
104
105
106
RLl
RLA4/Rm
Standoff = 1.5 in.
3.0
2.5
2.0
Rt /RLA4
1.5
1.0
0.5
0
10 –1
*Mark of Schlumberger
© Schlumberger
100
101
102
103
RLA4/Rm
Purpose
This chart is used to similarly to Chart RLl-2 to correct HRLA HighResolution Laterolog Array resistivity for borehole and drilling mud
effects. RLA4 is the apparent resistivity from computed focusing
mode 4.
113
Resistivity Laterolog—Wireline
HRLA* High-Resolution Laterolog Array
RLl-14
Borehole Correction—Open Hole
Tool Centered
3.0
2.5
2.0
Rt /RLA5
1.5
1.0
0.5
0
10 –1
100
101
102
103
104
105
106
RLA5/Rm
Standoff = 0.5 in.
3.0
dh
5 in.
6 in.
8 in.
9 in.
10 in.
12 in.
14 in.
16 in.
18 in.
20 in.
22 in.
2.5
RLl
2.0
Rt /RLA5
1.5
1.0
0.5
0
10 –1
100
101
102
103
104
105
106
104
105
106
RLA5/Rm
Standoff = 1.5 in.
3.0
2.5
2.0
Rt /RLA5
1.5
1.0
0.5
0
10 –1
*Mark of Schlumberger
© Schlumberger
100
101
102
103
RLA5/Rm
Purpose
This chart is used to similarly to Chart RLl-2 to correct HRLA HighResolution Laterolog Array resistivity for borehole and drilling mud
114
effects. RLA5 is the apparent resistivity from computed focusing
mode 5.
Resistivity Laterolog—LWD
GeoSteering* Bit Resistivity—6.75-in. Tool
RLl-20
Borehole Correction—Open Hole
1.2
1.1
1.0
0.9
Rt/Ra
0.8
0.7
24-in. bit
18-in. bit
12-in. bit
0.5
0
10–2
10–1
100
102
101
103
104
105
Ra/Rm
RLl
1.2
1.1
1.0
0.9
Rt/Ra
0.8
0.7
24-in. bit
18-in. bit
12-in. bit
0.6
0.5
10–2
10–1
100
101
102
103
104
105
Ra/Rm
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to derive the borehole correction for the GeoSteering
bit-measured resistivity. The bit resistivity corrected to the true
resistivity (Rt) is then used in the calculation of water saturation.
Description
Enter the chart on the x-axis with the ratio of the bit resistivity and
mud resistivity (Ra /Rm) at formation temperature. Move upward to
intersect the appropriate bit size. Move horizontally left to intersect
the correction factor on the y-axis. Multiply the correction factor by
the Ra value to obtain Rt. Charts RLl-21, RLl-23, and RLl-24 are similar to Chart RLl-20 for different tools and bit sizes.
Chart RLl-22 differs in that it is for reaming-down mode as
opposed to drilling mode.
115
Resistivity Galvanic—Drillpipe
Laterolog–LWD
GeoSteering* arcVISION675* Resistivity—6.75-in. Tool
RLl-21
Borehole Correction—Open Hole
1.2
1.1
1.0
0.9
Rt /Ra
0.8
0.7
0.5
0
10–2
24-in. bit
18-in. bit
12-in. bit
10–1
100
102
101
103
104
105
Ra /Rm
RLl
1.2
1.1
1.0
Rt /Ra
0.9
0.8
0.7
24-in. bit
18-in. bit
12-in. bit
0.6
0.5
10–2
10–1
100
101
102
Ra /R m
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart RLl-20 to derive the borehole
correction for the GeoSteering bit-measured arcVISION675
resistivity.
116
103
104
105
Resistivity Laterolog—LWD
GeoSteering* Bit Resistivity in Reaming Mode—6.75-in. Tool
RLl-22
Borehole Correction—Open Hole
1.5
1.4
Bit
1.3
1.2
1.1
Rt /Ra
1.0
arcVISION* tool
0.9
0.8
0.7
RLl
0.6
0.5
10–2
10–1
100
101
102
103
104
105
Ra /Rm
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart RLl-20 to derive the borehole
correction for the GeoSteering bit-measured resistivity while reaming down.
117
Resistivity Laterolog—LWD
geoVISION* Resistivity Sub—6.75-in. Tool
RLl-23
Borehole Correction—Open Hole
Ring Resistivity (with 81⁄2-in. bit)
2
Deep Button Resistivity (with 81⁄2-in. bit)
2
Borehole diameter (in.)
Borehole diameter (in.)
18
15
14
16
15
Rt/Ra
14
12
13
12
1
100
101
103
102
13
Rt /Ra
10
11
1
8.5
104
105
100
101
102
Ra /Rm
2
Borehole diameter (in.)
12
10
11
Rt/Ra
9.5
Rt /Ra
10.5
9.25
9.5
1
101
103
102
104
9
1
8.5
100
105
101
102
Ra /Rm
8.5
103
105
104
Ra /Rm
Bit Resistivity (with 81⁄2-in. bit)
ROP to Bit Face = 4 ft
2
105
104
Shallow Button Resistivity (with 81⁄2-in. bit)
2
Borehole diameter (in.)
13
100
8.5
Ra /Rm
Medium Button Resistivity (with 81⁄2-in. bit)
RLl
103
10
Bit Resistivity (with 81⁄2-in. bit)
ROP to Bit Face = 35 ft
2
Borehole diameter (in.)
Borehole diameter (in.)
22
20
22
18
Rt/Ra
16
18
14
12
1
100
*Mark of Schlumberger
© Schlumberger
101
103
102
16
10
104
1
8.5
105
Ra /Rm
Purpose
This chart is used similarly to Chart RLl-20 to derive the borehole
correction for the bit-measured resistivity from the GVR* resistivity
118
20
Rt/Ra
100
101
102
103
14
12
104
10
8.5
105
Ra /Rm
sub of the geoVISION 6.75-in. tool. The bottom row of charts
specifies the bit readout point (ROP) to the bit face.
Resistivity Laterolog—LWD
geoVISION* Resistivity Sub—8.25-in. Tool
RLl-24
Borehole Correction—Open Hole
Ring Resistivity (with 121⁄4-in. bit)
2
Deep Button Resistivity (with 121⁄4-in. bit)
2
Borehole diameter (in.)
Borehole diameter (in.)
22
20
20
Rt/Ra
Rt /Ra
19
19
18
17
18
17
1
12.25
100
102
101
103
16
16
15
1
100
105
104
101
102
Ra /Rm
13
14
1
103
102
13.5
Rt/Ra
15
2
RLl
14
16
101
105
Borehole diameter (in.)
17
100
104
Shallow Button Resistivity (with 121⁄4-in. bit)
2
Borehole diameter (in.)
Rt/Ra
12.25
Ra /Rm
Medium Button Resistivity (with 121⁄4-in. bit)
2
103
14
13.5
12.75
1
12.25
104
12.25
100
105
101
103
102
104
Ra /Rm
Ra /Rm
Bit Resistivity (with 121⁄4-in. bit)
ROP to Bit Face = 4 ft
Bit Resistivity (with 121⁄4-in. bit)
ROP to Bit Face = 35 ft
2
Borehole diameter (in.)
105
Borehole diameter (in.)
26
24
Rt/Ra
22
20
1
100
*Mark of Schlumberger
© Schlumberger
101
103
102
26
Rt/Ra
18
16
14
24
22
18
1
12.25
104
105
Ra /Rm
Purpose
This chart is used similarly to Chart RLl-20 to derive the borehole
correction for the bit-measured resistivity from the GVR* resistivity
100
101
102
103
20
16 14
12.25
104
105
Ra /Rm
sub of the geoVISION 8.25-in. tool. The bottom row of charts
specifies the bit readout point (ROP) to the bit face.
119
RGal-25.EPS
Resistivity Laterlog—LWD
GeoSteering* Bit Resistivity—6.75-in. Tool
RLl-25
Distance Out of Formation—Open Hole
600
10 ohm-m/4° BUR
100 ohm-m/4° BUR
10 ohm-m/5° BUR
500
100 ohm-m/5° BUR
10 ohm-m/10° BUR
400
Distance (ft)
300
200
100
RLl
0
0
2
4
6
8
10
12
Dip angle (°)
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to calculate the distance the GeoSteering bit must
travel to return to the target formation.
Example
Given:
Description
When drilling is at very high angles from vertical, the bit may wander
out of formation. If this occurs, how far the bit must travel to get
back into the formation must be determined.
Enter the chart with the known dip angle of the formation on
the x-axis. Move upward to intersect the appropriate “buildup rate”
(BUR) curve. Move horizontally left from the intersection point to
the y-axis and read the distance back into the formation.
Find:
Answer:
120
Formation dip angle = 6°, formation resistivity during
drilling = 10 ohm-m, and buildup rate = 4°.
Distance to return to the target formation.
Enter the chart at 6° on the x-axis. Move upward to the
10 ohm-m/4° BUR curve. Move horizontally left to the
y-axis to read approximately 290 ft.
Resistivity Laterolog—Wireline
General
CHFR* Cased Hole Formation Resistivity Tool
Rgal-50.EPSRLl-50
Cement Correction—Cased Hole
CHFR Cement Correction Chart (4.5-in.-OD casing)
1.6
No cement
0.5 in.
1.4
0.75 in.
1.5 in.
3 in.
1.2
5 in.
1.0
Rt /Rchfr
0.8
0.6
RLl
0.4
0.2
0
10 –2
10 –1
100
101
10 2
Rchfr /Rcem
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to correct the raw cased hole resistivity measurement of the CHFR Cased Hole Formation Resistivity tool (Rchfr) for
the thickness of the cement sheath. The resulting value of true resistivity (Rt) is used to calculate the water saturation.
Description
Enter the chart on the x-axis with the ratio of Rchfr and the resistivity
of the cement sheath (Rcem). The value of Rcem is obtained with labo­
ratory measurements. Move upward to the appropriate cement
sheath thickness curve, which represents the annular space between
the outside of the casing and the borehole wall. Move horizontally
left to the y-axis and read the Rt/Rchfr value. Multiply this value by
Rchfr to obtain Rt.
Charts RLl-51 and RLl-52 are for making the correction in larger
casing sizes.
121
General Laterolog—Wireline
Resistivity
CHFR* Cased Hole Formation Resistivity Tool
RLl-51
Cement Correction—Cased Hole
CHFR Cement Correction Chart (7-in.-OD casing)
1.6
No cement
0.5 in.
1.4
0.75 in.
1.5 in.
3 in.
1.2
5 in.
1.0
Rt /Rchfr
0.8
0.6
RLl
0.4
0.2
0
10 –2
10 –1
100
Rchfr /Rcem
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart RLl-50 to obtain the cased hole
resistivity of the CHFR Cased Hole Formation Resistivity tool corrected for the thickness of the cement sheath in 7-in.-OD casing.
122
101
10 2
Resistivity Laterolog—Wireline
CHFR* Cased Hole Formation Resistivity Tool
RLl-52
Cement Correction—Cased Hole
CHFR Cement Correction Chart (9.625-in.-OD casing)
1.6
No cement
0.5 in.
1.4
0.75 in.
1.5 in.
3 in.
1.2
5 in.
1.0
Rt /Rchfr
0.8
0.6
RLl
0.4
0.2
0
10 –2
10 –1
100
101
10 2
Rchfr /Rcem
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart RLl-50 to obtain the cased hole
resistivity of the CHFR Cased Hole Formation Resistivity tool corrected for the thickness of the cement sheath in 9.625-in.-OD casing.
123
Resistivity Galvanic—Wireline
Induction—Wireline
AIT* Array Induction Imager Tool
Operating Range—Open Hole
Purpose
This chart is used to determine the limit of application for the AIT
Array Induction Imager Tool measurement in a salt-saturated borehole.
Description
When the AIT tool logs a large salt-saturated borehole, the 10- and
20-in. induction curves may well be unusable because of the large
conductive borehole. In a borehole with a diameter (dh) of 8 in.,
the 10- and 20-in. curve data are usable if Rt < 300Rm. The ratio
of the true resistivity to the mud resistivity (Rt /Rm) is proportional
to (dh /8)2.
A general rule is that a 12-in. borehole must have a ratio of Rt /Rm
≤ 133 to have usable shallow log data. Additional requirements are
that the borehole must be round and the AIT tool standoff is 2.5 in.
The value of Rt /Rm is further reduced if the borehole is irregular or
the standoff requirement is not met.
Chart RInd-1 summarizes these requirements. The expected
values of Rt, Rm, borehole size, and standoff size are entered to
accurately determine the usable resolution in a smooth hole. The
lower chart summarizes which AIT resistivity tools typically provide
the most accurate deep resistivity data.
RInd
Example: Salt-Saturated Borehole
Given:
Borehole size = 10 in., Rt = 5 ohm-m, Rm =
0.0135 ohm-m, and standoff (so) = 2.5 in.
Find:
Which, if any, of the AIT curves are valid.
Answer:
From the x-axis equation:
2
 R t   d h   1.5 
 R   8   so  =
 m    
2
 5   10   1.5 
 0.0135   8   2.5  =
(370 )(1.5625 )( 0.6 ) = 346.
124
Enter the chart on the x-axis at 346 and move upward
to intersect Rt = 5 ohm-m on the y-axis. The intersection
point is in an error zone for which the shallow induction
curves are not valid even in a round borehole. The
deeper induction curves are valid only with a 2-ft or
larger vertical resolution.
The limits for the 1-, 2-, and 4-ft curves are integral to the chart.
As illustrated, a 1-ft 90-in. curve is not usable in a large salt-saturated
borehole. Also, under these conditions, the 1-, 2-, and 4-ft curves cannot have the same resistivity response.
Example: Freshwater Mud Borehole
Given:
Borehole size = 10 in., Rt = 5 ohm-m, Rm = 0.135 ohm-m,
and standoff (so) = 1.5 in.
Find:
Which, if any, of the AIT curves are valid.
Answer:
Rt /Rm = 37.0, (dh /8)2 = (10/8)2 = 1.5625, and (1.5/so) =
1.5/1.5 = 1. The resulting value from the x-axis equation
is 37.0 × 1.5625 × 1 = 57.9.
Enter the chart at 57.9 on the x-axis and intersect
Rt = 5 ohm-m on the y-axis. The intersection point is
within the limit of the 1-ft vertical resolution boundary.
All the AIT induction curves are usable.
Resistivity Induction—Wireline
AIT* Array Induction Imager Tool
RInd-1
Operating Range—Open Hole
1,000
Limit of 4-ft logs
Possible large errors on shallow logs and 2-ft limit
Limit of 1-ft logs
100
Rt
(ohm-m)
10
Recommended AIT operating range in
smooth holes (water-base mud: compute
standoff, oil-base mud: compute Rm)
Laterolog
use
recommended
Freshwater
mud example
Salt saturated
borehole example
1
0.01
0.1
1
Possible large errors
on all logs
10
100
1,000
10,000
 Rt   dh   1.5 
    
 Rm   8   so 
2
RInd
10,000
1,000 AIT 4-ft limit
AIT 2-ft limit
100 AIT 1-ft limit
Rt
(ohm-m)
1
0.01
AIT and
HRLA*
tools
AIT
tools
0.1
1
HRLA
tools
10
100
1,000
10,000
100,000
Rt/Rm
*Mark of Schlumberger
© Schlumberger
125
Resistivity Induction—Wireline
AIT* Array Induction Imager Tool
Borehole Correction—Open Hole
Introduction
The AIT tools (AIT-B, AIT-C, AIT-H, AIT-M, Slim Array Induction
Imager Tool [SAIT], Hostile Environment Induction Imager Tool
[HIT], and SlimXtreme* Array Induction Imager Tool [QAIT]) do not
have chartbook corrections for environmental effects. The normal
effects that required correction charts in the past (borehole correction, shoulder effect, and invasion interpretation) are now all made
using real-time algorithms for the AIT tools. In reality, the charts for
the older dual induction tools were inadequate for the complexity of
environmental effects on induction tools. The very large volume of
investigation required to obtain an adequate radial depth of investigation to overcome invasion makes the resulting set of charts too extensive for a book of this size. The volume that affects the logs can be tens
of feet above and below the tool. To make useful logs, the effects of the
volume above and below the layer of interest must be carefully removed.
This can be done only by either signal processing or inversion-based
processing. This section briefly describes the wellsite processing and
advanced processing available at computing centers.
RInd
Wellsite Processing
Borehole Correction
The first step of AIT log processing is to correct the raw data from
all eight arrays for borehole effects. Borehole corrections for the AIT
tools are based on inversion through an iterative forward model to
find the borehole parameters that best reproduce the logs from the
four shortest arrays—the 6-, 9-, 12-, and 15-in. arrays (Grove and
Minerbo, 1991). The borehole forward model is based on a solution
to Maxwell’s equations in a cylindrical borehole of radius r with the
mud resistivity (Rm) surrounded by a homogeneous formation of
resistivity R f. The tool can be located anywhere in the borehole, but
is parallel to the borehole axis at a certain tool standoff (so). The
borehole is characterized by its radius (r). In this model, the signal
in a given AIT array is a function of only these four parameters.
The four short arrays overlap considerably in their investigation depth, so only two of the borehole parameters can be uniquely
deter­mined in an inversion. The others must be supplied by outside
mea­surements or estimates. Because the greatest sensitivity to the
formation resistivity is in the contrast between Rm and R f, no external measurement is satisfactory for fitting to R f. Therefore, R f is
always solved for. This leaves one other parameter that can be determined. The three modes of the borehole correction operation depend
on which parameter is being determined:
■ compute mud resistivity: requires hole diameter and standoff
■ compute hole diameter: requires a mud resistivity measurement
and standoff
■ compute standoff: requires hole diameter and mud resistivity
measurement.
126
Because the AIT borehole model is a circular hole, either axis
from a multiaxis caliper can be used. If the tool standoff is adequate,
the process finds the circular borehole parameters that best match
the input logs. Control of adequate standoff is important because
the changes in the tool reading are very large for small changes in
tool position when the tool is very close to the borehole wall. Near
the center of the hole the changes are very small. A table of recommended standoff sizes is as follows.
AIT Tool Recommended Standoff
Hole Size (in.)
<5.0
5.0 to 5.5
5.5 to 6.5
6.5 to 7.75
7.75 to 9.5
9.5 to 11.5
>11.5
Recommended Standoff (in.)
AIT-B, AIT-C, AIT-H, AIT-M, HIT
SAIT, QAIT
–
0.5
–
1.0
0.5
1.5
1.0
2.0
1.5
2.5
2.0 + bowspring†
2.5
2.5 + bowspring†
2.5
Note: Do not run AIT tools slick.
† Only for AIT-H tool
Each type of AIT tool requires a slightly different approach to
the borehole correction method. For example, the AIT-B tool requires
the use of an auxiliary Rm measurement (Environmental
Measurement Sonde [EMS]) to compute Rm or to compute hole
size by using a recalibration of the mud resistivity method internal
to the borehole correction algorithm. The Platform Express*,
SlimAccess*, and Xtreme* AIT tools have integral Rm sensors that
meet the accuracy requirements for the compute standoff mode.
Log Formation
AIT tools are designed to produce a high-resolution log response
with reduced cave effect in comparison with the induction log deep
(ILD) in most formations. The log processing (Barber and Rosthal,
1991) is a weighted sum of the raw array data:
()
σ log z =
N
z = z max
Σ Σ
n =1 z = z
min
n
wn z ′ σ (a ) z − z ′ ,
( )
(
)
where Σlog (z) is the output log conductivity in mS/m, Σa(n) is the
skin-effect-corrected conductivity from the nth array, and the
weights (w) represent a deconvolution filter applied to each of the
raw array measurements. The log depth is z, and z′ refers to the
distance above or below the log depth to where the weights are
applied. The skin effect correction consists of fitting the X-signal
to the skin-effect-error signal (Moran, 1964; Barber, 1984) at high
conductivities and the R-signal to the error signal at low conductivi-
Resistivity Induction—Wireline
AIT* Array Induction Imager Tool
Borehole Correction—Open Hole
ties, with the crossover occurring between 100 and 200 mS/m. The
use of the R-signal at low conductivities overcomes the errors in
the X-signal associated with the normal magnetic susceptibilities
of sedimentary rock layers (Barber et al., 1995).
The weights w in the equation can profit from further refinement. The method used to compute the weights introduces a small
amount of noise in the matrix inversion, so the fit is about ±1% to
±2% to the defined target response. A second refinement filter is
used to correct for this error. The AIT wellsite processing sequence,
from raw, calibrated data to corrected logs, is shown in Fig. 1.
(Freedman and Minerbo, 1991, 1993; Zhang et al., 1994). MaximumEntropy Resistivity Log Inversion (MERLIN) processing (Barber et
al., 1999) follows Freedman and Minerbo (1991) closely, and that
paper is the basic reference for the mathematical formulation. The
problem is set up as the simplest parametric model that can fit the
data: a thinly layered formation with each layer the same thickness
(Fig. 2). The inversion problem is to solve for the conductivity of
each layer so that the computed logs from the layered formation
are the closest match to the measured logs.
R-signals only
14
or
8
A(H)IFC
28 channels
(AIT-B, -C, and -D)
16 channels
(all others)
Borehole
correction
28
or
16
Five depths
(10 to 90 in.)
Exception
handling and
environmentally
compensated
log processing
+
Caliper
Rm
Standoff
Multichannel
signal
processing
and 2D
processing
R-signals
X-signals
28
or
16
Skin
effect
correction
Five depths
(10 to 90 in.)
10 in.
20 in.
30 in.
60 in.
90 in.
Rm
RInd
Caliper
Raw BHC signals
Figure 1. Block diagram of the real-time log processing chain from raw, calibrated array data to finished logs.
There are only two versions of this processing—one for AIT-B,
AIT-C, and AIT-D tools and one for all other AIT tools (AIT-H, AIT-M,
SAIT, HIT, and QAIT) (Anderson and Barber, 1995). Only two versions are required because the tools were carefully designed with
the same coil spacings to produce the same two-dimensional (2D)
response to the formation.
Advanced Processing
Logs in Deviated Wells or Dipping Formations
The interpretation of induction logs is complicated by the large volume of investigation of these tools. The AIT series of induction tools
is carefully focused to limit the contributions from outside a relatively thin layer of response (Barber and Rosthal, 1991). In beds
at high relative dip, the focused response cuts across several beds,
and the focusing developed for vertical wells no longer isolates the
response to a single layer. The effect of the high relative dip angle is
to blur the response and to introduce horns at the bed boundaries.
Maximum Entropy Inversion: MERLIN Processing
The maximum entropy inversion method was first applied by Dyos
(1987) to induction log data. For beds at zero dip angle, it has been
shown to give well-controlled results when applied to deep induction
(ID) and medium induction (IM) from the dual induction tool
Well path
z
θ
∆z
R1
φ
y
x
ρ
Rn
Figure 2. The parametric model used in MERLIN inversion. All layers are the
same thickness, and the inversion solves for the conductivity of each layer
with maximum-entropy constraints.
127
Resistivity Induction—Wireline
AIT* Array Induction Imager Tool
Borehole Correction—Open Hole
The flow of MERLIN processing is shown in Fig. 3. The boreholecorrected raw resistive and reactive (R- and X-) signals are used as
a starting point. The conductivity of a set of layers is estimated from
the log values, and the iterative modeling is continued until the logs
converge. The set of formation layer conductivity values is then converted to resistivity and output as logs.
28 or 16 channels
Borehole-corrected
R- and X-signals
Initial guess
Invasion Processing
The wellsite interpretation for invasion is a one-dimensional (1D)
inversion of the processed logs into a four-parameter invasion model
(Rxo, Rt, r1, and r2, shown in Fig. 4). The forward model is based on
the Born model of the radial response of the tools and is accurate for
most radial contrasts in which induction logs should be used. The
inversion can be run in real time. The model is also available in the
Invasion Correction module of the GeoFrame* Invasion 2 application,
which also includes the step-invasion model and annulus model (Fig. 4).
Step Profile
Model parameters
Rxo
Forward model
Rt
Compute
Lagrangian
Computed log
ri
Sensitivity
matrix
Distance from wellbore
Slope Profile
RInd
Computed
log within 1%
of measured
log?
No
Rxo
Update model
parameters
Yes
Exit
Write model
parameters
as log
Formation
resistivity
profile
r1
Rt
r2
Distance from wellbore
Figure 3. Data flow in the MERLIN inversion algorithm. The output is the final
set of model parameters after the iterations converge.
Annulus Profile
Rann
Rxo
r1
r2
Rt
Figure 4. Parametric models used in AIT invasion processing. The slope
profile model is used for real-time processing; the others are available at the
computing centers. Rxo = resistivity of the flushed zone, Rt = true resistivity,
ri = radius of invasion, Rann = resistivity of the annulus.
128
Resistivity Induction—Wireline
AIT* Array Induction Imager Tool
Borehole Correction—Open Hole
Another approach is also used in the Invasion 2 application module. If the invaded zone is more conductive than the noninvaded
zone, some 2D effects on the induction response can complicate
the 1D inversion. Invasion 2 conducts a full 2D inversion using a
2D forward model (Fig. 5) to produce a more accurate answer for
situations of conductive invasion and in thin beds.
∞
Rm
Rt0
Rxo1
Rt1
Rxo2
Rt2
Rm
∞
Figure 5. The parametric 2D formation model used in Invasion 2.
References
Anderson, B., and Barber, T.: Induction Logging, Sugar Land, TX,
USA, Schlumberger SMP-7056 (1995).
Barber, T.D.: “Phasor Processing of Induction Logs Including
Shoulder and Skin Effect Correction,” US Patent No. 4,513,376
(September 11, 1984).
Barber, T., et al.: “Interpretation of Multiarray Induction Logs in
Invaded Formations at High Relative Dip Angles,” The Log Analyst,
(May–June 1999) 40, No. 3, 202–217.
Barber, T., Anderson, B., and Mowat, G.: “Using Induction Tools to
Identify Magnetic Formations and to Determine Relative Magnetic
Susceptibility and Dielectric Constant,” The Log Analyst (July–
August 1995) 36, No. 4, 16–26.
Barber, T., and Rosthal, R.: “Using a Multiarray Induction Tool to
Achieve Logs with Minimum Environmental Effects,” paper SPE 22725
presented at the SPE Annual Technical Conference and Exhibition,
Dallas, Texas, USA (October 6–9, 1991).
Dyos, C.J.: “Inversion of the Induction Log by the Method of Maximum
Entropy,” Transactions of the SPWLA 28th Annual Logging
Symposium, London, UK (June 29–July 2, 1987), paper T.
Freedman, R., and Minerbo, G.: “Maximum Entropy Inversion of the
Induction Log,” SPE Formation Evaluation (1991), 259–267; also
paper SPE 19608 presented at the SPE Annual Technical Conference
and Exhibition, San Antonio, TX, USA (October 8–11, 1989).
Freedman, R., and Minerbo, G.: “Method and Apparatus for
Producing a More Accurate Resistivity Log from Data Recorded by an
Induction Sonde in a Borehole,” US Patent 5,210,691 (January 1993).
Grove, G.P., and Minerbo, G.N.: “An Adaptive Borehole Correction
Scheme for Array Induction Tools,” Transactions of the SPWLA 32nd
Annual Logging Symposium, Midland, Texas, USA (June 16–19,
1991), paper P.
Moran, J.H.: “Induction Method and Apparatus for Investigating
Earth Formations Utilizing Two Quadrature Phase Components of
a Detected Signal,” US Patent No. 3,147,429 (September 1, 1964).
Zhang, Y-C., Shen, L., and Liu, C.: “Inversion of Induction Logs Based
on Maximum Flatness, Maximum Oil, and Minimum Oil Algorithms,”
Geophysics (September 1994), 59, No. 9, 1320–1326.
129
RInd
Resistivity Electromagnetic—LWD
arcVISION475* and ImPulse* 43⁄4-in. Array
Resistivity Compensated Tools—2 MHz
Borehole Correction—Open Hole
Purpose
This chart is used to determine the borehole correction applied
by the surface acquisition system to arcVISION475 and ImPulse
phase-shift (Rps) and attenuation resistivity (Rad) curves on the
log. The value of Rt is used in the calculation of water saturation.
Example
Given:
Description
Enter the appropriate chart for the borehole environmental conditions and tool used to measure the various formation resistivities
with the either the uncorrected phase-shift or attenuation resistivity
value (not the resistivity shown on the log) on the x-axis. Move upward
to intersect the appropriate resistivity spacing line, and then move
horizontally left to read the ratio value on the y-axis. Multiply the
ratio value by the resistivity value entered on the x-axis to obtain Rt.
Charts REm-12 through REm-38 are used similarly to Chart
REm-11 for different borehole conditions and arcVISION* and
ImPulse tool combinations.
Find:
Answer:
REm
130
Rps = 400 ohm-m (uncorrected) from arcVISION475
(2-MHz) phase-shift 10-in. resistivity, borehole size =
6 in., and mud resistivity (Rm) = 0.02 ohm-m at formation temperature.
Formation resistivity (Rt).
Enter the top left chart at 400 ohm-m on the x-axis
and move upward to intersect the 10-in. resistivity
curve (green).
Move left and read approximately 1.075 on the y-axis.
Rt = 1.075 × 400 = 430 ohm-m.
Resistivity Electromagnetic—LWD
arcVISION475* and ImPulse* 43⁄4-in. Array
Resistivity Compensated Tools—2 MHz
REm–11
Borehole Correction—Open Hole
arcVISION475 and ImPulse Borehole Correction for 2 MHz, dh = 6 in., Rm = 0.02 ohm-m
2.0
2.0
1.5
1.5
Rt/Rad
Rt/Rps
1.0
0.5
10–1
1.0
100
101
102
0.5
10–1
103
100
101
102
103
102
103
102
103
Rad (ohm-m)
Rps (ohm-m)
arcVISION475 and ImPulse Borehole Correction for 2 MHz, dh = 6 in., Rm = 0.1 ohm-m
2.0
2.0
1.5
1.5
Rt/Rps
Rt/Rad
1.0
0.5
10–1
1.0
100
101
102
0.5
10–1
103
100
101
REm
Rad (ohm-m)
Rps (ohm-m)
arcVISION475 and ImPulse Borehole Correction for 2 MHz, dh = 6 in., Rm = 1.0 ohm-m
2.0
2.0
1.5
1.5
Rt/Rps
Rt/Rad
1.0
0.5
10–1
1.0
100
101
102
103
0.5
10–1
100
101
Rps (ohm-m)
Resistivity spacing (in.)
Rad (ohm-m)
10
16
22
28
34
*Mark of Schlumberger
© Schlumberger
131
Resistivity Electromagnetic—LWD
arcVISION475* and ImPulse* 43⁄4-in. Array
Resistivity Compensated Tools—2 MHz
REm-12
Borehole Correction—Open Hole
arcVISION475 and ImPulse Borehole Correction for 2 MHz, dh = 7 in., Rm = 0.02 ohm-m
2.0
2.0
1.5
1.5
Rt /Rad
Rt /Rps
1.0
0.5
1.0
10 –1
100
101
102
0.5
103
10 –1
100
101
102
103
10 2
10 3
10 2
10 3
Rad (ohm-m)
Rps (ohm-m)
arcVISION475 and ImPulse Borehole Correction for 2 MHz, dh = 7 in., Rm = 0.1 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
0.5
REm
1.0
10 –1
10 0
10 1
10 2
0.5
10 3
10 –1
10 0
10 1
Rps (ohm-m)
Rad (ohm-m)
arcVISION475 and ImPulse Borehole Correction for 2 MHz, dh = 7 in., Rm = 1.0 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
0.5
1.0
10 –1
10 0
10 1
10 2
10 3
0.5
10 –1
10 0
10 1
Rad (ohm-m)
Rps (ohm-m)
Resistivity spacing (in.)
10
16
22
28
34
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
132
to arcVISION475 and ImPulse resistivity measurements. Uncorrected
resistivity is entered on the x-axis, not the resistivity shown on the log.
Resistivity Electromagnetic—LWD
arcVISION475* and ImPulse* 43⁄4-in. Array
Resistivity Compensated Tools—2 MHz
REm-13
Borehole Correction—Open Hole
arcVISION475 and ImPulse Borehole Correction for 2 MHz, dh = 8 in., Rm = 0.02 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
0.5
1.0
10 –1
100
101
102
0.5
103
10 –1
100
101
102
103
10 2
10 3
10 2
10 3
Rad (ohm-m)
Rps (ohm-m)
arcVISION475 and ImPulse Borehole Correction for 2 MHz, dh = 8 in., Rm = 0.1 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10 –1
10 0
10 1
10 2
0.5
10 3
10 –1
10 0
10 1
Rps (ohm-m)
REm
Rad (ohm-m)
arcVISION475 and ImPulse Borehole Correction for 2 MHz, dh = 8 in., Rm = 1.0 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
0.5
10 –1
1.0
10 0
10 1
10 2
10 3
0.5
10 –1
10 0
10 1
Rps (ohm-m)
*Mark of Schlumberger
© Schlumberger
Resistivity spacing (in.)
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
Rad (ohm-m)
10
16
22
28
34
to arcVISION475 and ImPulse resistivity measurements. Uncorrected
resistivity is entered on the x-axis, not the resistivity shown on the log.
133
Resistivity Electromagnetic—LWD
arcVISION475* and ImPulse* 43⁄4-in. Array
Resistivity Compensated Tools—2 MHz
REm-14
Borehole Correction—Open Hole
arcVISION475 and ImPulse Borehole Correction for 2 MHz, dh = 10 in., Rm = 0.02 ohm-m
2.0
2.0
1.5
1.5
Rt /Rad
Rt /Rps
1.0
1.0
0.5
10 –1
100
101
102
0.5
103
100
10 –1
Rps (ohm-m)
101
102
103
10 2
10 3
10 2
10 3
Rad (ohm-m)
arcVISION475 and ImPulse Borehole Correction for 2 MHz, dh = 10 in., Rm = 0.1 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
REm
10 –1
10 0
10 1
10 2
0.5
10 3
10 –1
10 0
10 1
Rad (ohm-m)
Rps (ohm-m)
arcVISION475 and ImPulse Borehole Correction for 2 MHz, dh = 10 in., Rm = 1.0 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
0.5
10 –1
1.0
10 0
10 1
10 2
10 3
0.5
10 –1
10 0
10 1
Rps (ohm-m)
Resistivity spacing (in.)
Rad (ohm-m)
10
16
22
28
34
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
134
to arcVISION475 and ImPulse resistivity measurements. Uncorrected
resistivity is entered on the x-axis, not the resistivity shown on the log.
Resistivity Electromagnetic—LWD
arcVISION675* 63⁄4-in. Array Resistivity Compensated Tool—400 kHz
REm-15
Borehole Correction—Open Hole
arcVISION675 Borehole Correction for 400 kHz, dh = 8 in., Rm = 0.02 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
0.5
1.0
10 –1
100
101
102
0.5
103
10 –1
100
101
Rps (ohm-m)
102
103
10 2
10 3
10 2
10 3
Rad (ohm-m)
arcVISION675 Borehole Correction for 400 kHz, dh = 8 in., Rm = 0.1 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
0.5
10 –1
10 0
10 1
10 2
10 3
10 0
10 –1
10 1
Rps (ohm-m)
REm
Rad (ohm-m)
arcVISION675 Borehole Correction for 400 kHz, dh = 8 in., Rm = 1.0 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10 –1
10 0
10 1
10 2
10 3
0.5
10 –1
10 0
10 1
Rps (ohm-m)
*Mark of Schlumberger
© Schlumberger
Resistivity spacing (in.)
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
Rad (ohm-m)
16
22
28
34
40
to arcVISION675 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
135
Resistivity Electromagnetic—LWD
arcVISION675* 63⁄4-in. Array Resistivity Compensated Tool—400 kHz
REm-16
Borehole Correction—Open Hole
arcVISION675 Borehole Correction for 400 kHz, dh = 10 in., Rm = 0.02 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
0.5
10 –1
1.0
100
101
102
0.5
10 –1
103
100
101
103
10 2
10 3
10 2
10 3
Rad (ohm-m)
Rps (ohm-m)
arcVISION675 Borehole Correction for 400 kHz, dh = 10 in., Rm = 0.1 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
0.5
10 –1
REm
102
1.0
10 0
10 1
10 2
0.5
10 –1
10 3
10 1
10 0
Rps (ohm-m)
Rad (ohm-m)
arcVISION675 Borehole Correction for 400 kHz, dh = 10 in., Rm = 1.0 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
0.5
10 –1
1.0
10 0
10 1
10 2
10 3
0.5
10 –1
10 0
10 1
Rps (ohm-m)
Resistivity spacing (in.)
Rad (ohm-m)
16
22
28
34
40
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
136
to arcVISION675 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
General Electromagnetic—LWD
Resistivity
arcVISION675* 63⁄4-in. Array Resistivity Compensated Tool—400 kHz
REm-17
Borehole Correction—Open Hole
2.0
2.0
1.5
1.5
Rt /Rad
1.0
0.5
1.0
10 –1
100
101
102
0.5
103
10 –1
100
101
102
103
10 2
10 3
Rad (ohm-m)
Rps (ohm-m)
arcVISION675 Borehole Correction for 400 kHz, dh = 12 in., Rm = 0.1 ohm-m
2.0
2.0
1.5
1.5
Rt /Rad
1.0
0.5
10 –1
1.0
10 0
10 1
10 2
0.5
10 3
10 –1
10 0
10 1
Rps (ohm-m)
REm
Rad (ohm-m)
arcVISION675 Borehole Correction for 400 kHz, dh = 12 in., Rm = 1.0 ohm-m
2.0
2.0
1.5
1.5
Rt /Rad
1.0
0.5
10 –1
1.0
10 0
10 1
10 2
10 3
0.5
10 –1
10 0
10 1
Rps (ohm-m)
Resistivity spacing (in.)
10 2
10 3
Rad (ohm-m)
16
22
28
34
40
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION675 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
137
Resistivity Electromagnetic—LWD
arcVISION675* 6 3⁄4-in. Array Resistivity Compensated Tool—400 kHz
REm-18
Borehole Correction—Open Hole
arcVISION675 Borehole Correction for 400 kHz, dh = 14 in., Rm = 0.02 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
0.5
1.0
10 –1
100
101
102
0.5
10 –1
103
100
101
102
103
10 2
10 3
10 2
10 3
Rad (ohm-m)
Rps (ohm-m)
arcVISION675 Borehole Correction for 400 kHz, dh = 14 in., Rm = 0.1 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
0.5
REm
1.0
10 –1
10 0
10 1
10 2
0.5
10 3
10 –1
10 0
10 1
Rps (ohm-m)
Rad (ohm-m)
arcVISION675 Borehole Correction for 400 kHz, dh = 14 in., Rm = 1.0 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
0.5
1.0
10 –1
10 0
10 1
10 2
10 3
0.5
10 –1
10 0
10 1
Rps (ohm-m)
Resistivity spacing (in.)
Rad (ohm-m)
16
22
28
34
40
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
138
to arcVISION675 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
Resistivity Electromagnetic—LWD
arcVISION675* 63⁄4-in. Array Resistivity Compensated Tool—2 MHz
REm-19
Borehole Correction—Open Hole
arcVISION675 Borehole Correction for 2 MHz, dh = 8 in., Rm = 0.02 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
0.5
1.0
10 –1
100
101
102
0.5
10 –1
103
100
101
Rps (ohm-m)
102
103
10 2
10 3
Rad (ohm-m)
arcVISION675 Borehole Correction for 2 MHz, dh = 8 in., Rm = 0.1 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
0.5
10 –1
1.0
10 0
10 1
10 2
0.5
10 –1
10 3
10 0
10 1
Rps (ohm-m)
REm
Rad (ohm-m)
arcVISION675 Borehole Correction for 2 MHz, dh = 8 in., Rm = 1.0 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
0.5
10 –1
1.0
10 0
10 1
10 2
0.5
10 –1
10 3
10 0
10 1
Rps (ohm-m)
Resistivity spacing (in.)
10 2
10 3
Rad (ohm-m)
16
22
28
34
40
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION675 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
139
Resistivity Electromagnetic—LWD
arcVISION675* 63⁄4-in. Array Resistivity Compensated Tool—2 MHz
REm-20
Bed Thickness Correction—Open Hole
arcVISION675 Borehole Correction for 2 MHz, dh = 10 in., Rm = 0.02 ohm-m
2.0
2.0
1.5
1.5
Rt/Rps
Rt/Rad
1.0
0.5
10–1
1.0
100
101
102
0.5
10–1
103
100
102
103
102
103
102
103
Rad (ohm-m)
Rps (ohm-m)
arcVISION675 Borehole Correction for 2 MHz, dh = 10 in., Rm = 0.1 ohm-m
2.0
2.0
1.5
1.5
Rt/Rps
Rt/Rad
1.0
0.5
10–1
REm
101
1.0
0.5
100
101
102
103
10–1
100
Rps (ohm-m)
101
Rad (ohm-m)
arcVISION675 Borehole Correction for 2 MHz, dh = 10 in., Rm = 1.0 ohm-m
2.0
2.0
1.5
1.5
Rt/Rps
Rt/Rad
1.0
0.5
10–1
1.0
100
101
102
0.5
10–1
103
100
Rps (ohm-m)
Resistivity spacing (in.)
101
Rad (ohm-m)
16
22
28
34
40
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
140
to arcVISION675 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
Resistivity Electromagnetic—LWD
arcVISION675* 63⁄4-in. Array Resistivity Compensated Tool—2 MHz
REm-21
Borehole Correction—Open Hole
arcVISION675 Borehole Correction for 2 MHz, dh = 12 in., Rm = 0.05 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10 –1
100
101
102
0.5
103
10 –1
100
101
Rps (ohm-m)
102
103
10 2
10 3
10 2
10 3
Rad (ohm-m)
arcVISION675 Borehole Correction for 2 MHz, dh = 12 in., Rm = 0.1 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10 –1
10 0
10 1
10 2
0.5
10 3
10 0
10 –1
10 1
Rps (ohm-m)
REm
Rad (ohm-m)
arcVISION675 Borehole Correction for 2 MHz, dh = 12 in., Rm = 1.0 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
0.5
1.0
10 –1
10 0
10 1
10 2
10 3
0.5
10 –1
10 0
10 1
Rad (ohm-m)
Rps (ohm-m)
Resistivity spacing (in.)
16
22
28
34
40
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION675 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
141
Resistivity Electromagnetic—LWD
arcVISION675* 63⁄4-in. Array Resistivity Compensated Tool—2 MHz
REm-22
Borehole Correction—Open Hole
arcVISION675 Borehole Correction for 2 MHz, dh = 14 in., Rm = 0.02 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
0.5
10 –1
1.0
100
101
102
0.5
10 –1
103
100
101
103
10 2
10 3
10 2
10 3
Rad (ohm-m)
Rps (ohm-m)
arcVISION675 Borehole Correction for 2 MHz, dh = 14 in., Rm = 0.1 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
0.5
10 –1
REm
102
1.0
10 0
10 1
10 2
0.5
10 3
10 –1
10 0
10 1
Rps (ohm-m)
Rad (ohm-m)
arcVISION675 Borehole Correction for 2 MHz, dh = 14 in., Rm = 1.0 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
0.5
10 –1
1.0
10 0
10 1
10 2
10 3
0.5
10 –1
10 0
10 1
Rps (ohm-m)
Resistivity spacing (in.)
Rad (ohm-m)
16
22
28
34
40
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
142
to arcVISION675 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
Resistivity Electromagnetic—LWD
arcVISION825* 81⁄4-in. Array Resistivity Compensated Tool—400 kHz
REm-23
Borehole Correction—Open Hole
arcVISION825 Borehole Correction for 400 kHz, dh = 10 in., Rm = 0.02 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
101
10 2
10 3
10 2
10 3
Rad (ohm-m)
arcVISION825 Borehole Correction for 400 kHz, dh = 10 in., Rm = 0.1 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
10 1
REm
Rad (ohm-m)
arcVISION825 Borehole Correction for 400 kHz, dh = 10 in., Rm = 1.0 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
Resistivity spacing (in.)
10 1
10 2
10 3
Rad (ohm-m)
16
22
28
34
40
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION825 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
143
Resistivity Electromagnetic—LWD
arcVISION825* 81⁄4-in. Array Resistivity Compensated Tool—400 kHz
REm-24
Bed Thickness Correction—Open Hole
arcVISION825 Borehole Correction for 400 kHz, dh = 12 in., Rm = 0.02 ohm-m
2.0
2.0
1.5
1.5
Rt /Rad
Rt /Rps
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
101
10 2
10 3
10 2
10 3
10 2
10 3
Rad (ohm-m)
arcVISION825 Borehole Correction for 400 kHz, dh = 12 in., Rm = 0.1 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
REm
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
10 1
Rad (ohm-m)
arcVISION825 Borehole Correction for 400 kHz, dh = 12 in., Rm = 1.0 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
Resistivity spacing (in.)
10 1
Rad (ohm-m)
16
22
28
34
40
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
144
to arcVISION825 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
Resistivity Electromagnetic—LWD
arcVISION825* 81⁄4-in. Array Resistivity Compensated Tool—400 kHz
REm-25
Borehole Correction—Open Hole
arcVISION825 Borehole Correction for 400 kHz, dh = 14 in., Rm = 0.02 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
101
10 2
10 3
10 2
10 3
Rad (ohm-m)
arcVISION825 Borehole Correction for 400 kHz, dh = 14 in., Rm = 0.1 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
10 1
REm
Rad (ohm-m)
arcVISION825 Borehole Correction for 400 kHz, dh = 14 in., Rm = 1.0 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
Resistivity spacing (in.)
10 1
10 2
10 3
Rad (ohm-m)
16
22
28
34
40
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION825 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
145
Resistivity Electromagnetic—LWD
arcVISION825* 81⁄4-in. Array Resistivity Compensated Tool—400 kHz
REm-26
Borehole Correction—Open Hole
arcVISION825 Borehole Correction for 400 kHz, dh = 18 in., Rm = 0.02 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
10 2
10 3
10 2
10 3
10 2
10 3
Rad (ohm-m)
arcVISION825 Borehole Correction for 400 kHz, dh = 18 in., Rm = 0.1 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
REm
101
10 0
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
10 1
Rad (ohm-m)
arcVISION825 Borehole Correction for 400 kHz, dh = 18 in., Rm = 1.0 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
Resistivity spacing (in.)
10 1
Rad (ohm-m)
16
22
28
34
40
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
146
to arcVISION825 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
Resistivity Electromagnetic—LWD
arcVISION825* 81⁄4-in. Array Resistivity Compensated Tool—2 MHz
REm-27
Borehole Correction—Open Hole
arcVISION825 Borehole Correction for 2 MHz, dh = 10 in., Rm = 0.02 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
101
10 2
10 3
10 2
10 3
10 2
10 3
Rad (ohm-m)
arcVISION825 Borehole Correction for 2 MHz, dh = 10 in., Rm = 0.1 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
10 1
REm
Rad (ohm-m)
arcVISION825 Borehole Correction for 2 MHz, dh = 10 in., Rm = 1.0 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
*Mark of Schlumberger
© Schlumberger
Resistivity spacing (in.)
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
10 1
Rad (ohm-m)
16
22
28
34
40
to arcVISION825 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
147
Resistivity Electromagnetic—LWD
arcVISION825* 81⁄4-in. Array Resistivity Compensated Tool—2 MHz
REm-28
Borehole Correction—Open Hole
arcVISION825 Borehole Correction for 2 MHz, dh = 12 in., Rm = 0.02 ohm-m
2.0
2.0
1.5
1.5
Rt /Rad
Rt /Rps
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
10 2
10 3
10 2
10 3
10 2
10 3
Rad (ohm-m)
arcVISION825 Borehole Correction for 2 MHz, dh = 12 in., Rm = 0.1 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
REm
101
10 0
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
10 1
Rad (ohm-m)
arcVISION825 Borehole Correction for 2 MHz, dh = 12 in., Rm = 1.0 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
Resistivity spacing (in.)
10 1
Rad (ohm-m)
16
22
28
34
40
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
148
to arcVISION825 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
Resistivity Electromagnetic—LWD
arcVISION825* 81⁄4-in. Array Resistivity Compensated Tool—2 MHz
REm-29
Borehole Correction—Open Hole
arcVISION825 Borehole Correction for 2 MHz, dh = 14 in., Rm = 0.02 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
101
10 2
10 3
10 2
10 3
10 2
10 3
Rad (ohm-m)
arcVISION825 Borehole Correction for 2 MHz, dh = 14 in., Rm = 0.1 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
10 1
REm
Rad (ohm-m)
arcVISION825 Borehole Correction for 2 MHz, dh = 14 in., Rm = 1.0 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
Resistivity spacing (in.)
10 1
Rad (ohm-m)
16
22
28
34
40
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION825 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
149
Resistivity Electromagnetic—LWD
arcVISION825* 81⁄4-in. Array Resistivity Compensated Tool—2 MHz
REm-30
Borehole Correction—Open Hole
arcVISION825 Borehole Correction for 2 MHz, dh = 18 in., Rm = 0.02 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rps
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
101
10 2
10 3
10 2
10 3
10 2
10 3
Rad (ohm-m)
arcVISION825 Borehole Correction for 2 MHz, dh = 18 in., Rm = 0.1 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rps
1.0
1.0
0.5
10–1
REm
10 0
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
10 1
Rad (ohm-m)
arcVISION825 Borehole Correction for 2 MHz, dh = 18 in., Rm = 1.0 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rps
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
Resistivity spacing (in.)
10 1
Rad (ohm-m)
16
22
28
34
40
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
150
to arcVISION825 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
Resistivity Electromagnetic—LWD
arcVISION900* 9-in. Array Resistivity Compensated Tool—400 kHz
REm-31
Borehole Correction—Open Hole
arcVISION900 Borehole Correction for 400 kHz, dh = 12 in., Rm = 0.02 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
101
10 2
10 3
10 2
10 3
10 2
10 3
Rad (ohm-m)
arcVISION900 Borehole Correction for 400 kHz, dh = 12 in., Rm = 0.1 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
10 1
REm
Rad (ohm-m)
arcVISION900 Borehole Correction for 400 kHz, dh = 12 in., Rm = 1.0 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
Resistivity spacing (in.)
10 1
Rad (ohm-m)
16
22
28
34
40
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION900 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
151
Resistivity Electromagnetic—LWD
­arcVISION900* 9-in. Array Resistivity Compensated Tool—400 kHz
REm-32
Borehole Correction—Open Hole
arcVISION900 Borehole Correction for 400 kHz, dh = 15 in., Rm = 0.02 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
101
Rps (ohm-m)
10 2
10 3
10 2
10 3
10 2
10 3
Rad (ohm-m)
arcVISION900 Borehole Correction for 400 kHz, dh = 15 in., Rm = 0.1 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
REm
10 0
10 1
10 2
0.5
10–1
10 3
10 0
10 1
Rps (ohm-m)
Rad (ohm-m)
arcVISION900 Borehole Correction for 400 kHz, dh = 15 in., Rm = 1.0 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
10 1
Rps (ohm-m)
Resistivity spacing (in.)
Rad (ohm-m)
16
22
28
34
40
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
152
to arcVISION900 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
Resistivity Electromagnetic—LWD
arcVISION900* 9-in. Array Resistivity Compensated Tool—400 kHz
REm-33
Borehole Correction—Open Hole
arcVISION900 Borehole Correction for 400 kHz, dh = 18 in., Rm = 0.02 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
101
Rps (ohm-m)
10 2
10 3
10 2
10 3
Rad (ohm-m)
arcVISION900 Borehole Correction for 400 kHz, dh = 18 in., Rm = 0.1 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
10 1
Rps (ohm-m)
REm
Rad (ohm-m)
arcVISION900 Borehole Correction for 400 kHz, dh = 18 in., Rm = 1.0 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
10 1
Rps (ohm-m)
Resistivity spacing (in.)
10 2
10 3
Rad (ohm-m)
16
22
28
34
40
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION900 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
153
Resistivity Electromagnetic—LWD
arcVISION900* 9-in. Array Resistivity Compensated Tool—400 kHz
REm-34
Borehole Correction—Open Hole
arcVISION900 Borehole Correction for 400 kHz, dh = 22 in., Rm = 0.02 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
10 2
10 3
10 2
10 3
10 2
10 3
Rad (ohm-m)
arcVISION900 Borehole Correction for 400 kHz, dh = 22 in., Rm = 0.1 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
REm
101
10 0
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
10 1
Rad (ohm-m)
arcVISION900 Borehole Correction for 400 kHz, dh = 22 in., Rm = 1.0 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
Resistivity spacing (in.)
10 1
Rad (ohm-m)
16
22
28
34
40
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
154
to arcVISION900 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
Resistivity Electromagnetic—LWD
arcVISION900* 9-in.Array Resistivity Compensated Tool—2 MHz
REm-35
Borehole Correction—Open Hole
arcVISION900 Borehole Correction for 2 MHz, dh = 12 in., Rm = 0.02 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
101
Rps (ohm-m)
10 2
10 3
10 2
10 3
Rad (ohm-m)
arcVISION900 Borehole Correction for 2 MHz, dh = 12 in., Rm = 0.1 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
10 1
Rps (ohm-m)
REm
Rad (ohm-m)
arcVISION900 Borehole Correction for 2 MHz, dh = 12 in., Rm = 1.0 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
10 1
Rps (ohm-m)
Resistivity spacing (in.)
10 2
10 3
Rad (ohm-m)
16
22
28
34
40
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION900 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
155
Resistivity Electromagnetic—LWD
arcVISION900* 9-in. Array Resistivity Compensated Tool—2 MHz
REm-36
Borehole Correction—Open Hole
arcVISION900 Borehole Correction for 2 MHz, dh = 15 in., Rm = 0.02 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
101
10 2
10 3
10 2
10 3
10 2
10 3
Rad (ohm-m)
arcVISION900 Borehole Correction for 2 MHz, dh = 15 in., Rm = 0.1 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
REm
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
10 1
Rad (ohm-m)
arcVISION900 Borehole Correction for 2 MHz, dh = 15 in., Rm = 1.0 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
Rps (ohm-m)
Resistivity spacing (in.)
10 1
Rad (ohm-m)
16
22
28
34
40
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
156
to arcVISION900 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
Resistivity Electromagnetic—LWD
arcVISION900* 9-in. Array Resistivity Compensated Tool—2 MHz
REm-37
Borehole Correction—Open Hole
arcVISION900 Borehole Correction for 2 MHz, dh = 18 in., Rm = 0.02 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10ñ1
10 0
10 1
10 2
0.5
10ñ1
10 3
10 0
101
Rps (ohm-m)
10 2
10 3
10 2
10 3
Rad (ohm-m)
arcVISION900 Borehole Correction for 2 MHz, dh = 18 in., Rm = 0.1 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10ñ1
10 0
10 1
10 2
0.5
10ñ1
10 3
10 0
10 1
Rps (ohm-m)
REm
Rad (ohm-m)
arcVISION900 Borehole Correction for 2 MHz, dh = 18 in., Rm = 1.0 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10ñ1
10 0
10 1
10 2
0.5
10ñ1
10 3
10 0
10 1
Rps (ohm-m)
Resistivity spacing (in.)
10 2
10 3
Rad (ohm-m)
16
22
28
34
40
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION900 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
157
Resistivity Electromagnetic—LWD
arcVISION900* 9-in. Array Resistivity Compensated Tool—2 MHz
REm-38
Borehole Correction—Open Hole
arcVISION900 Borehole Correction for 2 MHz, dh = 22 in., Rm = 0.02 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
101
Rps (ohm-m)
10 2
10 3
10 2
10 3
10 2
10 3
Rad (ohm-m)
arcVISION900 Borehole Correction for 2 MHz, dh = 22 in., Rm = 0.1 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
REm
10 1
10 2
0.5
10–1
10 3
10 0
10 1
Rps (ohm-m)
Rad (ohm-m)
arcVISION900 Borehole Correction for 2 MHz, dh = 22 in., Rm = 1.0 ohm-m
2.0
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
10–1
10 0
10 1
10 2
0.5
10–1
10 3
10 0
10 1
Rps (ohm-m)
Resistivity spacing (in.)
Rad (ohm-m)
16
22
28
34
40
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
158
to arcVISION900 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
Resistivity Electromagnetic—LWD
arcVISION675*, arcVISION825*, and arcVISION900*
Array Resistivity Compensated Tools—400 kHz
Bed Thickness Correction—Open Hole
Purpose
This chart is used to determine the correction factor applied by the
surface acquisition system for bed thickness to the phase-shift and
attenuation resistivity on the logs of arcVISION675, arcVISION825,
and arcVISION900 tools.
Description
The six bed thickness correction charts on this page are paired for
phase-shift and attenuation resistivity at different values of true (Rt)
and shoulder bed (Rs) resistivity. Only uncorrected resistivity values
are entered on the chart, not the resistivity shown on the log.
Chart REm-56 is also used to find the bed thickness correction
applied by the surface acquisition system for 2-MHz arcVISION* and
ImPulse* logs.
Example
Given:
Find:
Answer:
Rt/Rs = 10/1, Rps uncorrected = 20 ohm-m (34 in.), and
bed thickness = 6 ft.
Rt.
The appropriate chart to use is the phase-shift resistivity
chart in the first row, for Rt = 10 ohm-m and Rs = 1 ohm-m.
Enter the chart on the x-axis at 6 ft and move upward
to intersect the 34-in. spacing line. The corresponding
value of R t/R ps is 1.6; Rt = 20 × 1.6 = 32 ohm-m.
REm
continued on next page
159
Resistivity Electromagnetic—LWD
arcVISION675*, arcVISION825*, and arcVISION900*
Array Resistivity Compensated Tools—400 kHz
REm-55
Bed Thickness Correction—Open Hole
arcVISION675, arcVISION825, and arcVISION900 400-kHz
Bed Thickness Correction for Rt = 10 ohm-m and Rs = 1 ohm-m at Center of Bed
Phase-Shift Resistivity
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
0.5
0
Attenuation Resistivity
2.0
0
2
4
6
8
10
12
14
0
16
0
2
4
6
Bed thickness (ft)
8
10
12
14
16
12
14
16
Bed thickness (ft)
arcVISION675, arcVISION825, and arcVISION900 400-kHz
Bed Thickness Correction for Rt = 1 ohm-m and Rs =10 ohm-m at Center of Bed
Phase-Shift Resistivity
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
0.5
REm
0
Attenuation Resistivity
2.0
0
2
4
6
8
10
12
14
0
16
0
2
4
6
Bed thickness (ft)
8
10
Bed thickness (ft)
arcVISION675, arcVISION825, and arcVISION900 400-kHz
Bed Thickness Correction for Rt = 100 ohm-m and Rs =10 ohm-m at Center of Bed
Phase-Shift Resistivity
2.0
1.5
Rt /Rps
1.0
0.5
0
0
2
4
6
8
10
12
14
16
Bed thickness (ft)
Resistivity spacing (in.)
*Mark of Schlumberger
© Schlumberger
160
16
22
28
34
40
Resistivity Electromagnetic—LWD
arcVISION* and ImPulse* Array Resistivity Compensated Tools—2 MHz
REm-56
Bed Thickness Correction—Open Hole
arcVISION and ImPulse 2-MHz Bed Thickness Correction for
Rt = 10 ohm-m and Rs =1 ohm-m at Center of Bed
Phase-Shift Resistivity
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
0.5
0
Attenuation Resistivity
2.0
0
2
4
6
8
10
12
14
0
16
0
2
4
Bed thickness (ft)
6
8
10
12
14
16
Bed thickness (ft)
arcVISION and ImPulse 2-MHz Bed Thickness Correction for
Rt = 1 ohm-m and Rs =10 ohm-m at Center of Bed
Phase-Shift Resistivity
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
0.5
0
Attenuation Resistivity
2.0
0
2
4
6
8
10
12
14
0
16
REm
0
2
4
Bed thickness (ft)
6
8
10
12
14
16
12
14
16
Bed thickness (ft)
arcVISION and ImPulse 2-MHz Bed Thickness Correction for
Rt = 100 ohm-m and Rs =10 ohm-m at Center of Bed
Phase-Shift Resistivity
2.0
1.5
1.5
Rt /Rps
Rt /Rad
1.0
1.0
0.5
0.5
0
Attenuation Resistivity
2.0
0
2
4
6
8
10
12
14
0
16
0
2
Bed thickness (ft)
Resistivity spacing (in.)
4
6
8
10
Bed thickness (ft)
16
22
28
34
40
*Mark of Schlumberger
© Schlumberger
161
Resistivity Electromagnetic—LWD
arcVISION675* and ImPulse* Array Resistivity
Compensated Tools—2 MHz and 16-in. Spacing
REm-58
Dielectric Correction—Open Hole
15
8.60
Rt
20
8.55
10,000
1,000
8.45
1
10
20
30
40
50
60
70
80
90
100
8.40
Attenuation
(dB)
100
70
50
30
8.50
8.35
125
8.30
150
o
175
8.25
200
REm
225
8.20
250
275
8.15
8.10
300
–1
0
1
2
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to estimate the true resistivity (Rt) and dielectric
correction (εr). Rt is used in water saturation calculation.
Description
Enter the chart with the uncorrected (not those shown on the
log) phase-shift and attenuation values from the arcVISION675 or
ImPulse resistivity tool. The intersection point of the two values is
used to determine Rt and the dielectric correction. Rt is interpolated
from the subvertical lines described by the dots originating at the
162
3
4
5
6
7
8
9
Phase shift (°)
listed Rt values. The εr is interpolated from the radial lines originating
from the εr values listed on the left-hand side of the chart. Charts
REm-59 through REm-62 are used to determine Rt and εr at larger
spacings.
Example
Given:
Find:
Answer:
Phase shift = 2° and attenuation = 8.45 dB for 16-in.
spacing.
Rt and εr.
Rt = 26 ohm-m and εr = 70 dB.
Resistivity Electromagnetic—LWD
arcVISION675* and ImPulse* Array Resistivity
Compensated Tools—2 MHz and 22-in. Spacing
REm-59
Dielectric Correction—Open Hole
20
15
6.9
10,000
1,000
6.7
100
70
50
Rt
30
6.8
1
10
20
30
40
50
60
Attenuation
(dB)
6.6
70
80
90
100
o
125
REm
150
6.5
175
200
225
250
6.4
275
300
6.3
–1
0
1
2
*Mark of Schlumberger
© Schlumberger
3
4
5
6
7
8
9
Phase shift (°)
Purpose
Charts REm-59 through REm-62 are identical to Chart REm-58
for determining Rt and εr at larger spacings of the arcVISION675
and ImPulse 2-MHz tools.
163
Resistivity Electromagnetic—LWD
arcVISION675* and ImPulse* Array Resistivity
Compensated Tools—2 MHz and 28-in. Spacing
REm-60
Dielectric Correction—Open Hole
20
5.5
30
5.4
5.3
10,000
1,000
100
70
50
Rt
1
10
20
30
40
50
5.2
60
70
80
o
o
90
Attenuation
(dB)
100
5.1
125
150
REm
175
200
5.0
225
250
275
4.9
4.8
–1
300
0
1
2
*Mark of Schlumberger
© Schlumberger
Purpose
Charts REm-59 through REm-62 are identical to Chart REm-58
for determining Rt and εr at larger spacings of the arcVISION675
and ImPulse 2-MHz tools.
164
3
4
Phase shift (°)
5
6
7
8
9
Resistivity Electromagnetic—LWD
arcVISION675* and ImPulse* Array Resistivity
Compensated Tools—2 MHz and 34-in. Spacing
REm-61
Dielectric Correction—Open Hole
15
4.7
30
20
4.6
Rt
4.4
10,000
1,000
100
70
50
4.5
1
10
20
30
Attenuation
(dB)
4.3
40
50
60
o
70
80
90
100
4.2
REm
125
150
4.1
175
200
225
250
4.0
275
300
3.9
–1
0
1
2
*Mark of Schlumberger
© Schlumberger
3
4
5
6
7
8
9
Phase shift (°)
Purpose
Charts REm-59 through REm-62 are identical to Chart REm-58
for determining Rt and εr at larger spacings of the arcVISION675
and ImPulse 2-MHz tools.
165
Resistivity Electromagnetic—LWD
arcVISION675* and ImPulse* Array Resistivity
Compensated Tools—2 MHz and 40-in. Spacing
REm-62
Dielectric Correction—Open Hole
15
4.0
30
20
3.9
Rt
100
70
50
3.8
10,000
1,000
3.7
1
10
3.6
20
30
40
o
Attenuation
(dB)
50
60
70
3.5
80
90
100
REm
125
3.4
150
175
200
3.3
225
250
275
3.2
3.1
–1
300
0
1
2
*Mark of Schlumberger
© Schlumberger
Purpose
Charts REm-59 through REm-62 are identical to Chart REm-58 for
determining Rt and εr at larger spacings of the arcVISION675 and
ImPulse 2-MHz tools.
166
3
4
Phase shift (°)
5
6
7
8
9
Resistivity Electromagnetic—LWD
arcVISION675* and ImPulse* Array Resistivity
Compensated Tools—2 MHz with Dielectric Assumption
REm-63
Dielectric Correction—Open Hole
Dielectric Effects of Standard Processed arcVISION675 or ImPulse Log
at 2 MHz with Dielectric Assumption
3.5
3.0
2.5
Resistivity
spacing
16 in.
22 in.
28 in.
34 in.
40 in.
ε1 = 2εr
Rt /Rps
2.0
o
Dielectric assumption
εr = 5 + 108.5R –0.35
1.5
1.0
ε2 = 0.5εr
0.5
10–1
10 0
10 2
10 1
10 3
10 4
Rps (ohm-m)
REm
3.5
3.0
2.5
Resistivity
spacing
16 in.
22 in.
28 in.
34 in.
40 in.
ε2 = 0.5εr
Rt /Rad
2.0
o
Dielectric assumption
εr = 5 + 108.5R –0.35
1.5
1.0
ε1 = 2εr
0.5
10–1
*Mark of Schlumberger
© Schlumberger
10 0
10 2
10 1
10 3
10 4
Rad (ohm-m)
167
General Resistivity—Wireline
Formation
Resistivity Galvanic
Rt-1
Invasion Correction—Open Hole
(former Rint-1)
Purpose
The charts in this chapter are used to determine the correction for
invasion effects on the following parameters:
■
■
■
If SwA and SwR are equal, the assumption of a step-contact invasion profile is indicated to be correct, and all values determined
(Sw, Rt, Rxo, and di) are considered good.
If SwA > SwR, either invasion is very shallow or a transition-type
invasion profile is indicated, and SwA is considered a good value for Sw.
If SwA < SwR, an annulus-type invasion profile may be indi­cated,
and a more accurate value of water saturation may be estimated
by using
1 tor of (SwA /SwR)1 ⁄4 is
The correction fac4 from the scale.


S
readily determined
S wcor = S wA  wA 
For more informa S wR  tion, see Reference 9.
diameter of invasion (di)
ratio of flushed zone to true resistivity (Rxo /Rt)
Rt from laterolog resistivity tools.
The Rxo/Rt and Rt values are used in the calculation of water
saturation.
Description
The invasion correction charts, also referred to as “tor­nado” or “butterfly” charts, assume a step-contact profile of invasion and that all
resistivity measurements have already been c­ orrected as necessary
for borehole effect and bed thickness by using the appropriate chart
from the “Resistivity Laterolog” chapter.
To use any of these charts, enter the y-axis and x-axis with the
required resistivity ratios. The point of intersection defines di, Rxo /Rt,
and Rt as a function of one resistivity ­measurement.
Saturation Determination in Clean Formations
Either of the chart-derived values of Rt and Rxo /Rt are used to find
values for the water saturation of the formation (Sw). The first of two
approaches is the S w -Archie (SwA), which is found using the Archie
saturation formula (or Chart SatOH-3) with the derived Rt value and
known values of the formation resistivity factor (FR) and the resistivity of the water (Rw). The Sw-ratio (SwR) is found by using Rxo /Rt and
Rmf /Rw as in Chart SatOH-4.
SwA/SwR
0.45
Rt
0.80
0.50
0.55
0.85
0.60
0.65
0.70
0.90
(SwA/SwR)
168
0.80
0.95
1⁄4
© Schlumberger
0.75
0.85
0.90
0.95
1.0
1.0
Formation Resistivity—Wireline
High-Resolution Azimuthal Laterolog Sonde (HALS)
Rt-2
Formation Resistivity and Diameter of Invasion—Open Hole
Thick Beds, 8-in. Hole, Rxo /Rm = 10
103
8
15
18
20
22
24
28
32
1,000
36
40
45
500
Rt /Rxo
50
60
200
102
80
100
100
50
HLLD/Rxo
120
di (in.)
20
101
10
5
2
100
0.5
0.2
Rt
10–1
100
101
102
HLLD/HLLS
© Schlumberger
Purpose
The resistivity values of HALS laterolog deep resistivity (HLLD),
HALS laterolog shallow resistivity (HLLS), and resistivity of the
flushed zone (Rxo) measured by the High-Resolution Azimuthal
Laterolog Sonde (HALS) are used with this chart to determine
values for diameter of invasion (di) and true resistivity (Rt).
Description
The conditions for which this chart is used are listed at the top. The
chart is entered with the ratios of HLLD/HLLS on the x-axis and
HLLD/Rxo on the y-axis. The intersection point defines di on the
dashed curves and the ratio of Rt /Rxo on the solid curves.
Example
Given:
Find:
Answer:
HLLD = 50 ohm-m, HLLS = 15 ohm-m, Rxo = 2.0 ohm-m,
and Rm = 0.2 ohm-m.
Rt and diameter of invasion.
Enter the chart with the values of HLLD/HLLS = 50/15 =
3.33 and HLLD/Rxo = 50/2 = 25.
The resulting point of intersection on the chart indicates
that Rt /Rxo = 35 and di = 34 in.
Rt = 35 × 2.0 = 70 ohm-m.
169
Formation Resistivity—Wireline
High-Resolution Azimuthal Laterolog Sonde (HALS)
Rt-3
Formation Resistivity and Diameter of Invasion—Open Hole
Thick Beds, 8-in. Hole, Rxo /Rm = 10
103
8
15
18
20
22
24
28
32
1,000
Rt /Rxo
36
40
45
500
50
60
200
102
80
100
100
120
50
di (in.)
HRLD/Rxo
20
101
10
5
2
100
0.5
0.2
Rt
10–1
100
101
102
HRLD/HRLS
© Schlumberger
Purpose
The resistivity values of high-resolution deep resistivity (HRLD), highresolution shallow resistivity (HRLS), and Rxo measured by the HALS
are used similarly to Chart Rt-2 to determine values for di and Rt.
170
Description
The conditions for which this chart is used are listed at the top. The
chart is entered with the ratios of HRLD/HRLS on the x-axis and
HRLD/Rxo on the y-axis. The intersection point defines di on the
dashed curves and the ratio of Rt /Rxo on the solid curves.
Formation Resistivity—LWD
geoVISION675* Resistivity
Rt-10
Formation Resistivity and Diameter of Invasion—Open Hole
Ring, Deep, and Medium Button Resistivity (6.75-in. tool)
Rxo /Rm = 50
dh = 8.5 in.
10
9
8
Rt /Rring
16
1.4
17 1.6
1.5
1.8 18
7
6
Rring /Rbm
24
di
14
4
50
30
3
2
2.4
20
3.0
22
15
1.3
5
2.0
70
100
Rt /Rxo
20
15
13
1.2
10
7
5
12
3
2
1
2
1
Rt
3
Rring /Rbd
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to determine the correction applied to the log
presentation of Rt and di determined from geoVISION675 ring (Rring)
and deep (R bd) and medium button (Rbm) resistivity values.
Description
Enter the chart with the ratios of R ring /Rbd on the x-axis and Rring /
Rbm on the y-axis. The intersection point defines di on the blue
dashed curves, Rt /Rring on the red curves, and Rt /Rxo on the black
curves. Charts Rt-11 through Rt-17 are similar to Chart Rt-10 for
different tool sizes, configurations, and resistivity terms.
Example
Given:
Find:
Answer:
Rring = 30 ohm-m, Rxo /Rm = 50, Rbd = 15 ohm-m, and
Rbm = 6 ohm-m.
Rt, di, and Rxo.
Enter the chart with values of Rring /Rbd = 30/15 = 2 on
the x-axis and Rring /Rbm = 30/6 = 5 on the y-axis to find
di = 22.5 in., Rt /Rring = 3.1, and Rt /Rxo = 50. From these
ratios, Rt = 3.1 × 30 = 93 ohm-m and Rxo = 93/50 =
1.86 ohm-m.
171
Formation Resistivity—LWD
geoVISION675* Resistivity
Rt-11
Formation Resistivity and Diameter of Invasion—Open Hole
Deep, Medium, and Shallow Button Resistivity (6.75-in. tool)
30
Rxo /Rm = 50
dh = 8.5 in.
di
Rt /Rbd
20
13
14
1.2
1.4
1.3
1.5
15
1.1
1.6
16
17
12
18
Rbd /Rbs
10
9
8
7
6
100
70
50
11
30
5
20
15
4
10
3
Rt /Rxo
7
2
5
3
2
1
Rt
1
1
2
3
Rbd /Rbm
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Rt-10 to determine the
correction applied to the log presentation of Rt and di determined
from geoVISION675 deep (Rbd), medium (Rbm), and shallow
button (Rbs) resistivity values.
172
4
5
6
Formation Resistivity—LWD
geoVISION675* Resistivity
Rt-12
Formation Resistivity and Diameter of Invasion—Open Hole
Bit, Ring, and Deep Button Resistivity (6.75-in. tool) with ROP to Bit Face = 4 ft
Rxo /Rm = 50
dh = 8.5 in.
10
9
8
Rt /Rbit
7
di
5
Rbit/Rbd
20
24
28 3.0
4.0
34
1.8
22
6
2.0
2.5
40
1.6
50
70
100
50
30
4
20
15
18
3
10
1.4
Rt /Rxo
7
2
5
16
3
2
1
1
1
2
3
4
5
6
7
Rt
8
Rbit /Rring
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Rt-10 to determine the correction applied to the log presentation of Rt and di determined from
geoVISION675 Rring, bit (Rbit), and Rbd resistivity values.
173
Formation Resistivity—LWD
geoVISION675* Resistivity
Rt-13
Formation Resistivity and Diameter of Invasion—Open Hole
Bit, Ring, and Deep Button Resistivity (6.75-in. tool) with ROP to Bit Face = 35 ft
20
Rxo /Rm = 50
dh = 8.5 in.
34 2.0
28
Rt /Rbit
1.6
50
70
100
1.4
70
24
50
10
9
8
7
Rbit /Rbd
2.4
22
1.3
6
20
20
di
5
30
15
4
3
7
1.2
5
16
2
Rt /Rxo
10
18
3
2
1
Rt
1
1
2
3
4
5
Rbit /Rring
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Rt-10 to determine the correction applied to the log presentation of Rt and di determined from
geoVISION675 Rring, Rbit, and Rbd resistivity values.
174
6
7
8
9 10
20
Formation Resistivity—LWD
geoVISION825* 81⁄4-in. Resistivity-at-the-Bit Tool
Rt-14
Formation Resistivity and Diameter of Invasion—Open Hole
Ring, Deep, and Medium Button Resistivity (81⁄4-in. tool)
10
9
Rxo /Rm = 50
dh = 12.25 in.
22
8
di
7
Rt /Rring
6
1.4
1.8
23
24
2.4
21
3.0
26
20
1.3
5
19
4
Rring /Rbm
50
3
70
100
30
30
18
20
1.2
2
1.6
15
Rt /Rxo
10
17
7
5
16
1
3
2
1
1
Rt
2
Rring /Rbd
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Rt-10 to determine the correction applied to the log presentation of Rt and di determined from
geoVISION825 Rring, Rbd, and Rbm resistivity values.
175
Formation Resistivity—LWD
geoVISION825* 81⁄4-in. Resistivity-at-the-Bit Tool
Rt-15
Formation Resistivity and Diameter of Invasion—Open Hole
Deep, Medium, and Shallow Button Resistivity (81⁄4-in. tool)
Rxo /Rm = 50
20 dh = 12.25 in.
Rt /Rbd
18
1.3
1.4
19
1.6
20
1.2 17
22
di
10
9
8
7
16
70
100
24
50
6
Rbd /Rbs
2.0
2.4
5
30
4
20
1.1
15
3
Rt /Rxo
10
7
2
5
3
14
2
1
Rt
1
1
2
Rbd /Rbm
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Rt-10 to determine the correction applied to the log presentation of Rt and di determined from
geoVISION825 Rbd, Rbm, and Rbs resistivity values.
176
3
4
5
Formation Resistivity—LWD
geoVISION825* 81⁄4-in. Resistivity-at-the-Bit Tool
Rt-16
Formation Resistivity and Diameter of Invasion—Open Hole
Bit, Ring, and Deep Button Resistivity (81⁄4-in. tool) with ROP to Bit Face = 4 ft
10
9
Rxo /Rm = 50
dh = 12.25 in.
Rt /Rbit
8
28
7
di
6
26
5
2.0
1.8
4
35
40
5.0
50
1.6
50
70
100
60
30
1.5
20
24
Rbit /Rbd
3.0
2.4
30
15
1.4
3
10
22
7
2
5
1.3
20
Rt /Rxo
3
2
1
1
1
2
3
4
5
6
7
Rt
8
Rbit /Rring
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Rt-10 to determine the correction applied to the log presentation of Rt and di determined from
geoVISION825 Rring, Rbit, and Rbd resistivity values.
177
Formation Resistivity—LWD
geoVISION825* 81⁄4-in. Resistivity-at-the-Bit Tool
Rt-17
Formation Resistivity and Diameter of Invasion—Open Hole
Bit, Ring, and Deep Button Resistivity (81⁄4-in. tool) with ROP to Bit Face = 35 ft
20
Rt /Rxo = 50
dh = 12.25 in.
40 2.0
35
Rt /Rbit
30
10
9
8
7
Rbit /Rbd
di
1.4
70
30
26
20
6
Rt /Rxo
15
5
24
4
3.0
70
100
50
28
1.3
1.6
50
10
1.2
7
3
22
5
2
20
3
2
1
Rt
1
1
2
3
4
Rbit /Rring
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Rt-10 to determine the correction applied to the log presentation of Rt and di determined from
geoVISION825 Rring, Rbit, and Rbd resistivity values.
178
5
6
7
8
9 10
20
Formation Resistivity—LWD
arcVISION* Array Resistivity Compensated Tool—400 kHz
Rt-31
Resistivity Anisotropy Versus Shale Volume—Open Hole
Response Through Sand and Shale Layers at 90° Relative Dip
for Rsh = 1 ohm-m and Rsand = 5 ohm-m
Response Through Sand and Shale Layers at 90° Relative Dip
for Rsh = 1 ohm-m and Rsand = 20 ohm-m
Phase-Shift Resistivity
101
Phase-Shift Resistivity
102
Rps
101
(ohm-m)
Rps
(ohm-m)
100
0
0.2
0.4
0.8
0.6
100
1.0
0.2
0
0.8
1.0
0.8
1.0
Vsh
Attenuation Resistivity
101
0.6
0.4
Vsh
Attenuation Resistivity
102
Rad
101
(ohm-m)
Rad
(ohm-m)
100
0
0.2
0.4
0.8
0.6
1.0
100
0.2
0
Vsh
Vsh
Resistivity spacing
0.6
0.4
16 in.
22 in.
Rh
Rv
28 in.
34 in.
Rt
40 in.
*Mark of Schlumberger
© Schlumberger
Purpose
This chart illustrates the resistivity response, as affected by sand
and shale layers, of the arcVISION tool in horizontal wellbores.
The chart is used to determine the values of Rh and Rv. These
corrections are already applied to the log presentation.
Description
The chart is constructed for shale layers at 90° relative dip to the
axis of the arcVISION tool. That is, both the layers of shale and the
tool are horizontal to the vertical. Other requirements for use of this
chart are that the shale resistivity (Rsh) is 1 ohm-m and the sand
resistivity is 5 or 20 ohm-m.
Select the appropriate chart for the attenuation (Rad) or phaseshift (Rps) resistivity and values of resistivity of the shale (Rsh) and
sand (Rsand). Enter the chart with the volume of shale (Vsh) on the
x-axis and the resistivity on the y-axis. At the intersection point of
these two values move straight downward to the dashed blue curve
to read the value of Rh. Move upward to the solid green curve to read
the value of Rv.
Chart Rt-32 is used to determine Rh and Rv values for the 2-MHz
resistivity.
179
Formation Resistivity—LWD
arcVISION* and ImPulse* Array Resistivity Compensated Tools—2 MHz
Rt-32
Resistivity Anisotropy Versus Shale Volume—Open Hole
Response Through Sand and Shale Layers at 90° Relative Dip
for Rsh = 1 ohm-m and Rsand = 5 ohm-m
Phase-Shift Resistivity
102
Rps
(ohm-m)
Rps
(ohm-m)
0
0.2
0.6
0.4
Phase-Shift Resistivity
102
101
100
Response Through Sand and Shale Layers at 90° Relative Dip
for Rsh = 1 ohm-m and Rsand = 20 ohm-m
0.8
101
100
1.0
0.2
0
0.4
Vsh
Attenuation Resistivity
102
Rad
(ohm-m)
Rt
Rad
(ohm-m)
0
0.2
0.6
0.4
0.8
1.0
100
0
0.2
0.4
0.6
0.8
1.0
Vsh
16 in.
22 in.
Rh
Rv
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Rt-31 for arcVISION and
ImPulse 2-MHz resistivity. These corrections are already applied
to the log presentation.
180
1.0
101
Vsh
Resistivity spacing
0.8
Attenuation Resistivity
102
101
100
0.6
Vsh
28 in.
34 in.
40 in.
Formation Resistivity—LWD
arcVISION* Array Resistivity Compensated Tool—400 kHz
Rt-33
Resistivity Anisotropy Versus Dip—Open Hole
Aniostropy Response for Rh = 1 ohm-m and (Rv /Rh) = 2
Aniostropy Response for Rh = 1 ohm-m and (Rv /Rh) = 5
Phase-Shift Resistivity
103
Phase-Shift Resistivity
101
102
Rps
(ohm-m)
Rps
(ohm-m)
101
100
0
10
20
30
40
50
60
70
80
100
90
0
10
20
Relative dip angle (°)
40
50
60
70
80
90
70
80
90
Relative dip angle (°)
Attenuation Resistivity
103
30
Attenuation Resistivity
101
102
Rad
(ohm-m)
Rad
(ohm-m)
101
100
0
10
20
30
40
50
60
70
80
100
90
0
10
Relative dip angle (°)
Resistivity spacing
20
30
40
50
60
Relative dip angle (°)
16 in.
22 in.
28 in.
34 in.
40 in.
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to determine arcVISION Rps and Rad for relative
dip angles from 0 to 90°. These corrections are already applied to
the log presentation.
Description
Enter the appropriate chart with the value of relative dip angle and
move to intersect the known resistivity spacing. Move horizontally
left to read Rps or Rad for the conditions of the horizontal resistivity
(Rh) = 1 ohm-m and the square root of the Rv/Rh ratio.
181
Rt
Formation Resistivity—LWD
arcVISION* and ImPulse* Array Resistivity Compensated Tools—2 MHz
Rt-34
Resistivity Anisotropy Versus Dip—Open Hole
Aniostropy Response for Rh = 1 ohm-m and (Rv /Rh) = 2
Aniostropy Response for Rh = 1 ohm-m and (Rv /Rh) = 5
Phase-Shift Resistivity
103
Phase-Shift Resistivity
101
102
Rps
(ohm-m)
Rps
(ohm-m)
101
100
0
10
20
30
40
50
60
70
80
100
90
0
10
20
Relative dip angle (°)
40
50
60
70
80
90
70
80
90
Relative dip angle (°)
Attenuation Resistivity
103
30
Attenuation Resistivity
101
102
Rad
(ohm-m)
Rad
(ohm-m)
101
100
Rt
0
10
20
30
40
50
60
70
80
100
90
0
10
Relative dip angle (°)
Resistivity spacing
30
40
50
60
Relative dip angle (°)
16 in.
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Rt-33 for arcVISION and
ImPulse 2-MHz resistivity. These corrections are already applied
to the log presentation.
182
20
22 in.
28 in.
34 in.
40 in.
Formation Resistivity—LWD
arcVISION* Array Resistivity Compensated Tool—400 kHz
Rt-35
Resistivity Anisotropy Versus Square Root of Rv/Rh—Open Hole
Aniostropy Response at 65° dip for Rh = 1 ohm-m
Aniostropy Response at 85° dip for Rh = 1 ohm-m
Phase-Shift Resistivity
103
Rps
(ohm-m)
Phase-Shift Resistivity
101
102
Rps
(ohm-m)
101
100
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
100
1.0
5.0
1.5
2.0
2.5
(Rv /Rh)
Rad
(ohm-m)
3.5
4.0
4.5
5.0
4.0
4.5
5.0
(Rv /Rh)
Attenuation Resistivity
103
3.0
Attenuation Resistivity
101
102
Rad
(ohm-m)
101
100
1.0
1.5
2.0
3.0
2.5
3.5
4.0
4.5
100
1.0
5.0
1.5
(Rv /Rh)
Resistivity spacing
2.0
2.5
3.0
3.5
(Rv /Rh)
16 in.
22 in.
28 in.
34 in.
40 in.
*Mark of Schlumberger
© Schlumberger
Purpose
This chart and Chart Rt-36 reflect the effect of anisotropy on the
arcVISION resistivity response. These corrections are already
applied to the log presentation. As the square root of the R v /Rh
ratio increases, the effect on the resistivity significantly increases.
Description
Enter the appropriate chart with the value of the phase-shift or
attenuation resistivity on the y-axis. Move horizontally to intersect
the resistivity spacing curve. At the intersection point read the value
of the square root of the R v /Rh ratio on the x-axis.
183
Rt
Formation Resistivity—LWD
arcVISION* and ImPulse* Array Resistivity Compensated Tools—2 MHz
Rt-36
Resistivity Anisotropy Versus Square Root of Rv/Rh—Open Hole
Aniostropy Response at 85° dip for Rh = 1 ohm-m
Aniostropy Response at 65° dip for Rh = 1 ohm-m
Phase-Shift Resistivity
103
Phase-Shift Resistivity
101
102
Rps
(ohm-m)
Rps
(ohm-m)
101
100
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
100
1.0
5.0
1.5
2.0
2.5
Attenuation Resistivity
103
3.0
3.5
4.0
4.5
5.0
4.0
4.5
5.0
(Rv/Rh)
(Rv/Rh)
Attenuation Resistivity
101
102
Rad
(ohm-m)
Rad
(ohm-m)
101
100
1.0
Rt
1.5
2.0
2.5
3.0
3.5
4.0
4.5
100
1.0
5.0
1.5
16 in.
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Rt-35 for arcVISION and
ImPulse for 2-MHz resistivity. These corrections are already
applied to the log presentation.
184
2.5
3.0
3.5
(Rv/Rh)
(Rv/Rh)
Resistivity spacing
2.0
22 in.
28 in.
34 in.
40 in.
Formation Resistivity—LWD
arcVISION675* Array Resistivity Compensated Tool—400 kHz
Rt-37
Conductive Invasion—Open Hole
Rxo and di for Rt ~ 10 ohm-m
1.0
7
5
64
3
40-in. Rad/Rt = 1
2
60
1.5
56
16-in. Rps /40-in. Rad
0.1
1
0.7
0.9
0.85
0.8
0.5 0.75
0.7
0.65
0.3 0.6
0.2 0.55
52
44
0.95
40
36
16
0.15
48
20
32
di (in.)
28
Rxo = 0.1 ohm−m
24
Rt
0.01
0.01
1.0
0.1
28-in. Rps /40-in. Rad
*Mark of Schlumberger
© Schlumberger
Purpose
This log-log chart is used to determine the correction applied to
the log presentation of the 40-in. arcVISION675 resistivity measurements, diameter of invasion (di), and resistivity of the flushed zone
(Rxo). These data are used to evaluate a formation for hydrocarbons.
Description
Enter the chart with the ratio of the 16-in. Rps /40-in. Rad on the y-axis
and 28-in. Rps /40-in. Rad on the x-axis. The intersection point defines
the following:
■
■
■
di
Rxo
correction factor for 40-in. attenuation resistivity.
Chart Rt-38 is used for 2-MHz resistivity values. The corresponding
charts for resistive invasion are Charts Rt-39 and Rt-40.
Example
Given:
Find:
Answer:
16-in. Rps/40-in. Rad = 0.2 and 28-in. Rps/40-in. Rad = 0.4.
Rxo, di, and correction factor for 40-in. Rad .
At the intersection point of 0.2 on the y-axis and 0.4 on
the x-axis, di = 31.9 in., Rxo = 1.1 ohm-m, and correction
factor = 0.955.
The value of the 40-in. Rad is reduced by the correction
factor: 40-in. Rad × 0.955.
185
Formation Resistivity—LWD
arcVISION675* and ImPulse* Array Resistivity Compensated Tools—2 MHz
Rt-38
Conductive Invasion—Open Hole
Rxo and di for Rt ~ 10 ohm-m
1.0
52
48
7
56
5
3
44
2
1.5
1
0.7
16
0.5
0.1
0.3
16-in. Rps /
40-in. Rad
40-in. Rad/Rt = 1
0.9
0.8
40
0.7
0.2
0.2
Rt
0.6
di (in.)
0.5
0.3
20
0.4
0.15
Rxo = 0.1 ohm-m
0.01
0.01
36
32
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Rt-37 for arcVISION675 and
ImPulse 2-MHz resistivity. The corrections are already applied to
the log presentation.
186
24
28
0.1
28-in. Rps /40-in. Rad
1.0
Formation Resistivity—LWD
arcVISION* Array Resistivity Compensated Tool—400 kHz
Rt-39
Resistive Invasion—Open Hole
Rxo and di for Rt ~ 10 ohm-m
10
125
100
90
Rxo = 300 ohm-m
80
75
200
70
0.55
150
65
0.6
60
0.65
55
16-in. Rps /
40-in. Rad
0.75
50
70
0.8
45
0.85
di (in.)
40
100
0.7
50
0.9
0.95
Rt /40-in. Rad = 1
Rt
30
35
30
20
15
1
1
*Mark of Schlumberger
© Schlumberger
10
28-in. Rps /40-in. Rad
Purpose
This chart is used similarly to Chart Rt-37 to determine the correction applied to the arcVISION log presentation of di, Rxo, and 40-in.
Rad for resistive invasion.
187
Formation Resistivity—LWD
arcVISION* and ImPulse* Array Resistivity Compensated Tools—2 MHz
Rt-40
Resistive Invasion—Open Hole
Rxo and di for Rt ~ 10 ohm-m
2.4
2.2
65
60
55
2.0
0.55
50
0.65
1.8
16-in. Rps /
40-in. Rad
100
0.7
40
di (in.)
70
0.75
1.6
150
0.6
45
Rxo = 300 ohm-m
200
35
50
0.8
Rt
30
1.4
30
0.85
0.9
0.95
20
1.2
15
1.0
Rt /40-in. Rad = 1
1
1.05
1.1
1.15
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Rt-39 to determine the correction applied to the arcVISION and ImPulse log presentation for
2-MHz resistivity.
188
1.2
28-in. Rps /40-in. Rad
1.25
1.3
1.35
1.4
Formation Resistivity—LWD
arcVISION* Array Resistivity Compensated Tool—400 kHz in Horizontal Well
Bed Proximity Effect—Open Hole
Purpose
Charts Rt-41 and Rt-42 are used to calculate the correction applied
to the log presentation of Rt from the arcVISION tool at the
approach to a bed boundary. The value of Rt is used to calculate
water saturation.
Description
There are two sets of charts for differing conditions:
■
shoulder bed resistivity (Rshoulder) = 10 ohm-m and Rt = 1 ohm-m
■
Rshoulder = 10 ohm-m and Rt =100 ohm-m.
Example
Given:
Find:
Answer:
Rshoulder = 10 ohm-m, Rt = 1 ohm-m, and
16-in. Rps = 1.5 ohm-m.
Bed proximity effect.
The top set of charts is appropriate for these resistivity
values. The ratio Rps /Rt = 1.5/1 = 1.5.
Enter the y-axis of the left-hand chart at 1.5 and move
horizontally to intersect the 16-in. curve. The corresponding value on the x-axis is 1 ft, which is the distance
of the surrounding bed from the tool. At 2 ft from the
bed boundary, the value of 16-in. R ps = 1 ohm-m.
Rt
continued on next page
189
Formation Resistivity—LWD
Resistivity–Drill Pipe
arcVISION* Array Resistivity Compensated Tool—400 kHz in Horizontal Well
Rt-41
Bed Proximity Effect—Open Hole
Bed Proximity Effect for Horizontal Well: Rshoulder = 10 ohm-m and Rt = 1 ohm-m
3
3
2
2
Rps /Rt
Rad /Rt
1
0
1
0
1
2
3
4
5
6
7
8
9
0
10
0
1
2
4
5
6
7
8
9
10
8
9
10
Bed Proximity Effect for Horizontal Well: Rshoulder = 10 ohm-m and Rt = 100 ohm-m
3
3
2
2
Rps /Rt
Rad /Rt
1
1
0
0
1
2
3
4
5
6
7
8
9
0
10
0
1
Resistivity spacing
*Mark of Schlumberger
© Schlumberger
16 in.
2
3
4
5
6
7
Distance to bed boundary (ft)
Distance to bed boundary (ft)
Rt
190
3
Distance to bed boundary (ft)
Distance to bed boundary (ft)
22 in.
28 in.
34 in.
40 in.
Formation Resistivity—LWD
arcVISION* and ImPulse* Array Resistivity Compensated Tools—2 MHz
in Horizontal Well
Rt-42
Bed Proximity Effect—Open Hole
Bed Proximity Effect for Horizontal Well: Rshoulder = 10 ohm-m, Rt = 1 ohm-m
3
3
2
2
Rad /Rt
Rps /Rt
1
0
1
0
1
2
3
4
5
6
7
8
9
0
10
0
1
2
3
4
5
6
7
8
9
10
8
9
10
Distance to bed boundary (ft)
Distance to bed boundary (ft)
Bed Proximity Effect for Horizontal Well: Rshoulder = 10 ohm-m, Rt = 100 ohm-m
3
3
2
2
Rad /Rt
Rps /Rt
1
1
0
0
1
2
3
4
5
6
7
8
9
0
10
0
1
16 in.
3
4
5
6
7
Distance to bed boundary (ft)
Distance to bed boundary (ft)
Resistivity spacing
2
22 in.
28 in.
34 in.
Rt
40 in.
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Rt-41 for arcVISION and
ImPulse 2-MHz resistivity. The correction is already applied
to the log presentation.
191
Lithology—Wireline
General
Density and NGS* Natural Gamma Ray Spectrometry Tool
Mineral Identification—Open Hole
Purpose
This chart is a method for identifying the type of clay in the wellbore.
The values of the photoelectric factor (Pe) from the Litho-Density*
log and the concentration of potassium (K) from the NGS Natural
Gamma Ray Spectrometry tool are entered on the chart.
Description
Enter the upper chart with the values of Pe and K to determine the
point of intersection. On the lower chart, plotting Pe and the ratio
of thorium and potassium (Th/K) provides a similar mineral evaluation. The intersection points are not unique but are in general areas
defined by a range of values.
Lith
192
Example
Given:
Find:
Answer:
Environmentally corrected thorium concentration
(ThNGScorr) = 10.6 ppm, environmentally corrected
potassium concentration (KNGScorr) = 3.9%, and Pe = 3.2.
Mineral concentration of the logged clay.
The intersection points from plotting values of Pe and K
on the upper chart and Pe and Th/K ratio = 10.6/3.9 = 2.7
on the lower chart suggest that the clay mineral is illite.
Lithology—Wireline
Density and NGS* Natural Gamma Ray Spectrometry Tool
Lith-1
Mineral Identification—Open Hole
(former CP-18)
10
8
Glauconite
Chlorite
Biotite
6
Photoelectric
factor, Pe
4
Illite
Muscovite
Montmorillonite
2
0
Kaolinite
0
2
4
6
8
10
Potassium concentration, K (%)
10
8
Glauconite
Biotite
Lith
Chlorite
6
Photoelectric
factor, Pe
4
Illite
Mixed layer
Muscovite
2
0
0.1
Montmorillonite
0.2
0.3
0.6
1
2
3
6
Kaolinite
10
20
30
60
100
Thorium/potassium ratio, Th/K
*Mark of Schlumberger
© Schlumberger
193
Lithology—Wireline
NGS* Natural Gamma Ray Spectrometry Tool
Lith-2
Mineral Identification—Open Hole
(former CP-19)
Heav
y tho
rium
-bea
ring
mine
rals
20
15
Thorium
(ppm)
12
Th/K
= 25
25
Th
/K
=
Possible 100% kaolinite,
montmorillonite,
illite “clay line”
Kaolinite
K=
Th/
lay
er c
-lay
d
e
Mix
M
on
tm
or
illo
nit
e
0
= 2.0
Th/K
~40%
mica
Illite
Micas
Glauconite
e
orit
Chl
0
3.5
~70% illite
10
5
100% illite point
1
2
3
~30% glauconite
Th/K = 0.6
Feldspar
Th/K = 0.3
Potassium evaporites, ~30% feldspar
4
5
Potassium (%)
*Mark of Schlumberger
© Schlumberger
Lith
Purpose
This chart is used to determine the type of minerals in a shale
formation from concentrations measured by the NGS Natural
Gamma Ray Spectrometry tool.
Description
Entering the chart with the values of thorium and potassium locates
the intersection point used to determine the type of radioactive minerals that compose the majority of the clay in the formation.
194
A sandstone reservoir with varying amounts of shaliness and
illite as the principal clay mineral usually plots in the illite segment
of the chart with Th/K between 2.0 and 3.5. Less shaly parts of the
reservoir plot closer to the origin, and shaly parts plot closer to the
70% illite area.
Lithology—Wireline
Platform Express* Three-Detector Lithology Density Tool
Porosity and Lithology—Open Hole
Purpose
This chart is used to determine the lithology and porosity of a formation. The porosity is used for the water saturation determination and
the lithology helps to determine the makeup of the logged formation.
Description
Note that this chart is designed for fresh water (fluid density
[ρf] = 1.0 g/cm3) in the borehole. Chart Lith-4 is used for saltwater
(ρf = 1.1 g/cm3) formations.
Values of photoelectric factor (Pe) and bulk density (ρb) from the
Platform Express Three-Detector Lithology Density (TLD) tool are
entered into the chart. At the point of intersection, porosity and
lithology values can be determined.
Example
Given:
Find:
Answer:
Freshwater drilling mud, Pe = 3.0, and bulk density =
2.73 g/cm3.
Freshwater drilling mud, Pe = 1.6, and bulk density =
2.24 g/cm3.
Porosity and lithology.
For the first set of conditions, the formation is a
dolomite with 8% porosity.
The second set is for a quartz sandstone formation
with 30% porosity.
Lith
continued on next page
195
Lithology—Wireline
Platform Express* Three-Detector Lithology Density Tool
Lith-3
Porosity and Lithology—Open Hole
(former CP-16)
Fresh Water (ρf = 1.0 g/cm3), Liquid-Filled Borehole
0
40
2.0
Salt
40
1.9
30
40
2.1
10
2.5
20
10
Bulk density, ρb
(g/cm3)
Dolomite
2.4
20
ne)
(limesto
Calcite
30
2.3
20
Quartz sandstone
30
2.2
0
2.6
10
Lith
0
2.7
0
2.8
0
Anhydrite
2.9
3.0
0
1
2
3
Photoelectric factor, Pe
*Mark of Schlumberger
© Schlumberger
196
4
5
6
Lithology—Wireline
Platform Express* Three-Detector Lithology Density Tool
Lith-4
Porosity and Lithology—Open Hole
(former CP-17)
Salt Water (ρf = 1.1 g/cm3), Liquid-Filled Borehole
1.9
40
40
0
Salt
2.0
Bulk density, ρb
(g/cm3)
10
20
10
2.5
Dolomite
2.4
20
ne)
(limesto
Calcite
30
2.3
20
Quartz sandstone
2.2
30
30
40
2.1
0
2.6
10
2.7
0
Lith
0
2.8
0
Anhydrite
2.9
3.0
0
1
2
*Mark of Schlumberger
© Schlumberger
This chart is used similarly to Chart Lith-3 for lithology and porosity determination with values of photoelectric factor (Pe) and
3
4
5
6
Photoelectric factor, Pe
bulk density (ρb) from the Platform Express TLD tool in saltwater
borehole fluid.
197
General
Lithology—Wireline,
Drillpipe
LWD
Density Tool
Lith-5
Apparent Matrix Volumetric Photoelectric Factor—Open Hole
(former CP-20)
Fresh water (0 ppm), ρf = 1.0 g/cm3, U f = 0.398
Salt water (200,000 ppm), ρf = 1.11 g/cm3, U f = 1.36
3.0
0
2.5
10
20
2.0
30
Bulk density, ρb
(g/cm3)
40
6
5
4
3
2
1
Photoelectric factor, Pe
4
6
8
10
12
Apparent total
porosity, φta (%)
14
Apparent matrix
volumetric photoelectric factor, Umaa
© Schlumberger
Lith
Purpose
This chart is used to determine the apparent matrix volumetric
photoelectric factor (Umaa) for the Chart Lith-6 percent lithology
determination.
Description
This chart is entered with the values of bulk density (ρb) and Pe from
a density log. The value of the apparent total porosity (ϕta) must also
be known. The appropriate solid lines on the right-hand side of the
chart that indicate a freshwater borehole fluid or dotted lines that
represent saltwater borehole fluid are used depending on the salinity
of the borehole fluid. Uf is the fluid photoelectric factor.
198
Example
Given:
Find:
Answer:
Pe = 4.0, ρb = 2.5 g/cm3, ϕta = 25%, and freshwater
borehole fluid.
Apparent matrix volumetric photoelectric factor (Umaa).
Enter the chart with the Pe value (4.0) on the left-hand
x-axis, and move upward to intersect the curve for
ρb = 2.5 g/cm3.
From that intersection point, move horizontally right to
intersect the ϕta value of 25%, using the blue freshwater
curve.
Move vertically downward to determine the Umaa value
on the right-hand x-axis scale: Umaa = 13.
Lithology—Wireline, LWD
General
Density Tool
Lithology Identification—Open Hole
Purpose
This chart is used to identify the rock mineralogy through comparison
of the apparent matrix grain density (ρmaa) and apparent matrix volumetric photoelectric factor (Umaa).
Description
The values of ρmaa and Umaa are entered on the y- and x-axis, respectively. The rock mineralogy is identified by the proximity of the point
of intersection of the two values to the labeled points on the plot.
The effect of gas, salt, etc., is to shift data points in the directions
shown by the arrows.
Example
Given:
Find:
Answer:
ρmaa = 2.74 g/cm3 (from Chart Lith-9 or Lith-10) and
Umaa = 13 (from Chart Lith-5).
Matrix composition of the formation.
Enter the chart with ρmaa = 2.74 g/cm3 on the y-axis and
Umaa = 13 on the x-axis. The intersection point indicates
a matrix mixture of 20% dolomite and 80% calcite.
Lith
continued on next page
199
Lithology—Wireline, LWD
General
Density Tool
Lith-6
Lithology Identification—Open Hole
(former CP-21)
2.2
2.3
Salt
on
Gas directi
2.4
2.5
K-feldspar
2.6
Apparent matrix
grain density,
ρmaa (g/cm3)
2.7
% calcit
e
20
Quartz
40
60
80
80
Calcite
60
%
tz
ar
qu
2.8
20
40
40
20
%
80
Barite
ite
lom
o
d
Dolomite
2.9
Lith
60
Heavy minerals
Anhydrite
3.0
Kaolinite
Illite
3.1
2
4
6
8
10
12
Apparent matrix volumetric photoelectric factor, Umaa
© Schlumberger
200
14
16
Lithology—Wireline, LWD
Environmentally Corrected Neutron Curves
M–N Plot for Mineral Identification—Open Hole
Purpose
This chart is used to help identify mineral mixtures from sonic,
density, and neutron logs.
Description
Because M and N slope values are practically independent of porosity except in gas zones, the porosity values they indicate can be
correlated with the mineralogy. (See Appendix E for the formulas to
calculate M and N from sonic, density, and neutron logs.)
Enter the chart with M on the y-axis and N on the x-axis. The
intersection point indicates the makeup of the formation. Points for
binary mixtures plot along a line connecting the two mineral points.
Ternary mixtures plot within the triangle defined by the three constituent minerals. The effect of gas, shaliness, secondary porosity,
etc., is to shift data points in the directions shown by the arrows.
The lines on the chart are divided into numbered groups by porosity range as follows:
1. ϕ = 0 (tight formation)
2. ϕ = 0 to 12 p.u.
3. ϕ = 12 to 27 p.u.
4. ϕ = 27 to 40 p.u.
Example
Given:
Find:
Answer:
M = 0.79 and N = 0.51.
Mineral composition of the formation.
The intersection of the M and N values indicates dolomite
in group 2, which has a porosity between 0 to 12 p.u.
Lith
continued on next page
201
Lithology—Wireline, LWD
Environmentally Corrected Neutron Curves
Lith-7
M–N Plot for Mineral Identification—Open Hole
(former CP-8)
1.1
Freshwater mud
ρf = 1.0 Mg/m3, t f = 620 µs/m
ρf = 1.0 g/cm3, t f = 189 µs/ft
Gypsum
Saltwater mud
ρf = 1.1 Mg/m3, t f = 607 µs/m
ρf = 1.1 g/cm3, t f = 185 µs/ft
1.0
s
Ga r
o lt
sa
Secondary
porosity
0.9
vma = 5943 m/s
= 19,500 ft/s
Quartz sandstone
Calcite (limestone)
0.8
1 2 34
Dolomite
M
324
vma = 5486 m/s
= 18,000 ft/s
1
Anhydrite
0.7
Sulfur
Approximate
shale
region
0.6
Lith
0.5
0.3
0.4
0.5
0.6
N
© Schlumberger
202
0.7
0.8
Lithology—Wireline
General
Environmentally Corrected APS* Curves
M–N Plot for Mineral Identification—Open Hole
Purpose
This chart is used to help identify mineral mixtures from APS
Accelerator Porosity Sonde neutron logs.
Description
Because M and N values are practically independent of porosity
except in gas zones, the porosity values they indicate can be correlated with the mineralogy. (See Appendix E for the formulas to
calculate M and N from sonic, density, and neutron logs.)
Enter the chart with M on the y-axis and N on the x-axis. The
intersection point indicates the makeup of the formation. Points for
binary mixtures plot along a line connecting the two mineral points.
Ternary mixtures plot within the triangle defined by the three constituent minerals. The effect of gas, shaliness, secondary porosity,
etc., is to shift data points in the directions shown by the arrows.
The lines on the chart are divided into numbered groups by porosity range as follows:
1. ϕ = 0 (tight formation)
2. ϕ = 0 to 12 p.u.
3. ϕ = 12 to 27 p.u.
4. ϕ = 27 to 40 p.u.
Because the dolomite spread is negligible, a single dolomite point
is plotted for each mud.
Example
Given:
Find:
Answer:
M = 0.80 and N = 0.55.
Mineral composition of the formation.
Dolomite.
Lith
continued on next page
203
Lithology—Wireline
General
Environmentally Corrected APS* Curves
Lith-8
M–N Plot for Mineral Identification—Open Hole
(former CP-8a)
1.1
Freshwater mud
ρf = 1.0 Mg/m3, t f = 620 µs/m
ρf = 1.0 g/cm3, t f = 189 µs/ft
Saltwater mud
ρf = 1.1 Mg/m3, t f = 607 µs/m
ρf = 1.1 g/cm3, t f = 185 µs/ft
Gypsum
1.0
s
Ga r
o lt
sa
Secondary
porosity
0.9
vma = 5943 m/s
= 19,500 ft/s
Quartz sandstone
Calcite (limestone)
0.8
12 3,4
Dolomite
vma = 5486 m/s
= 18,000 ft/s
M
Anhydrite
0.7
Sulfur
Approximate
shale
region
0.6
Lith
0.5
0.3
0.4
0.5
0.6
N
*Mark of Schlumberger
© Schlumberger
204
0.7
0.8
Lithology—Wireline, LWD
Bulk Density or Interval Transit Time and Apparent Total Porosity
Apparent Matrix Parameters—Open Hole
Purpose
Charts Lith-9 (customary units) and Lith-10 (metric units) provide
values of the apparent matrix internal transit time (t maa) and apparent matrix grain density (ρmaa) for the matrix identification (MID)
Charts Lith-11 and Lith-12. With these parameters the identification
of rock mineralogy or lithology through a comparison of neutron,
density, and sonic measurements is possible.
Example
Given:
Find:
Answer:
Apparent crossplot porosity from density-neutron = 20%,
ρb = 2.4 g /cm3, apparent crossplot porosity from
neutron-sonic = 30%, and t = 82 μs/ft.
ρmaa and t maa.
ρmaa = 2.75 g/cm3 and t maa = 46 μs/ft.
Description
Determining the values of t maa and ρmaa to use in the MID Charts
Lith-11 and Lith-12 requires three steps.
First, apparent crossplot porosity is determined using the appropriate neutron-density and neutron-sonic crossplot charts in the
“Porosity” section of this book. For data that plot above the sandstone curve on the charts, the apparent crossplot porosity is defined
by a vertical projection to the sandstone curve.
Second, enter Chart Lith-9 or Lith-10 with the interval transit
time (t) to intersect the previously determined apparent crossplot
porosity. This point defines t maa.
Third, enter Chart Lith-9 or Lith-10 with the bulk density (ρb)
to again intersect the apparent crossplot porosity and define ρmaa.
The values determined from Charts Lith-9 and Lith-10 for t maa and
ρmaa are cross plotted on the appropriate MID plot (Charts Lith-11
and Lith-12) to identify the rock mineralogy by its proximity to the
labeled points on the plot.
Lith
continued on next page
205
Lithology—Wireline, LWD
Bulk Density or Interval Transit Time and Apparent Total Porosity
Lith-9
Apparent Matrix Parameters—Open Hole
(customary, former CP-14)
Fluid Density = 1.0 g/cm3
Apparent matrix transit time, t maa (µs/ft)
130
3.0
120
110
100
90
80
70
60
50
40
30
130
2.9
120
2.8
110
40
2.7
10
2.5
2.4
70
60
20
2.2
50
30
2.1
2.0
40
40
3.0
2.9
2.8
2.7
2.6
2.5
2.4
Apparent matrix density, ρmaa (g/cm3)
© Schlumberger
206
80
10
2.3
Lith
90
20
De
ns
ity
-n
eu
tro
n
Bulk density,
ρb (g/cm3)
Ne
ut
ro
nso
ni
c
2.6
100
Apparent
crossplot
porosity
30
2.3
2.2
2.1
2.0
30
Interval
transit
time,
t (µs/ft)
General
Lithology—Wireline,
LWD
Bulk Density or Interval Transit Time and Apparent Total Porosity
Lith-10
Apparent Matrix Parameters—Open Hole
(metric, former CP-14m)
Fluid Density = 1.0 g/cm3
Apparent matrix transit time, t maa (µs/m)
3.0
350
325
300
275
250
225
200
175
150
125
100
2.9
325
40
2.8
2.7
30
Ne
ut
ro
nso
ni
c
2.6
Apparent
crossplot
porosity
275
250
20
10
2.5
2.4
225
175
20
2.2
150
30
2.1
125
40
3.0
2.9
Interval
transit
time,
t (µs/m)
200
10
2.3
2.0
300
De
ns
ity
-n
eu
tro
n
Bulk density,
ρb (g/cm3)
350
2.8
2.7
2.6
2.5
2.4
2.3
2.2
2.1
2.0
Lith
100
Apparent matrix density, ρmaa (g/cm3)
© Schlumberger
Purpose
Charts Lith-9 (customary units) and Lith-10 (metric units) provide
values of the apparent matrix internal transit time (t maa) and apparent matrix grain density (ρmaa) for the matrix identification (MID)
Charts Lith-11 and Lith-12. With these parameters the identification
of rock mineralogy or lithology through a comparison of neutron,
density, and sonic measurements is possible.
207
Lithology—Wireline, LWD
General
Density Tool
Matrix Identification (MID)—Open Hole
Purpose
Charts Lith-11 and Lith-12 are used to establish the type of mineral
predominant in the formation.
Description
Enter the appropriate (customary or metric units) chart with
the values established from Charts Lith-9 or Lith-10 to identify the
predominant mineral in the formation. Salt points are defined for
two tools, the sidewall neutron porosity (SNP) and the CNL*
Compensated Neutron Log. The presence of secondary porosity
in the form of vugs or fractures displaces the data points parallel
to the apparent matrix internal transit time (t maa ) axis. The presence
of gas displaces points to the right on the chart. Plotting some shale
points to establish the shale trend lines helps in the identification
of shaliness. For fluid density (ρf) other than 1.0 g/cm3 use the table
to determine the multiplier to correct the apparent total density
porosity before entering Chart Lith-11 or Lith-12.
Lith
208
Example
Given:
Find:
Answer:
ρf
Multiplier
1.00
1.05
1.10
1.15
1.00
0.98
0.95
0.93
ρmaa = 2.75 g/cm3, t maa = 56 μs/ft (from Chart Lith-9),
and ρf = 1.0 g/cm3.
The predominant mineral.
The formation consists of both dolomite and calcite,
which indicates a dolomitized limestone. The formation
used in this example is from northwest Florida in the
Jay field. The vugs (secondary porosity) created by the
dolomitization process displace the data point parallel
to the dolomite and calcite points.
General
Lithology—Wireline,
LWD
Density Tool
Lith-11
Matrix Identification (MID)—Open Hole
(customary, former CP-15)
2.0
Salt
(SNP)
2.1
Salt
(CNL* log)
2.2
2.3
2.4
on
cti
ire
d
s
Ga
2.5
ρmaa
(g/cm3)
2.6
Quartz
2.7
Calcite
2.8
Dolomite
2.9
Anhydrite
3.0
Lith
3.1
30
40
50
60
70
tmaa (µs/ft)
*Mark of Schlumberger
© Schlumberger
209
Lithology—Wireline, LWD
Density Tool
Lith-12
Matrix Identification (MID)—Open Hole
(metric, former CP-15m)
2.0
Salt
(CNL* log)
Salt
(SNP)
2.1
2.2
2.3
2.4
on
cti
ire
d
s
Ga
2.5
ρmaa
(g/cm3)
2.6
Quartz
2.7
Calcite
2.8
Dolomite
2.9
Anhydrite
3.0
Lith
3.1
100
120
140
160
t maa (µs/m)
*Mark of Schlumberger
© Schlumberger
Purpose
Chart Lith-12 is used similarly to Chart Lith-11 to establish the mineral
type of the formation.
210
180
200
220
240
Porosity—Wireline, LWD
General
Sonic Tool
Porosity Evaluation—Open Hole
Purpose
This chart is used to convert sonic log slowness time (Δt) values
into those for porosity (ϕ).
Description
There are two sets of curves on the chart. The blue set for matrix
velocity (vma) employs a weighted-average transform. The red set
is based on the empirical observation of lithology (see Reference
20). For both, the saturating fluid is assumed to be water with
a velocity (vf) of 5,300 ft/s (1,615 m/s).
Enter the chart with the slowness time from the sonic log on the
x-axis. Move vertically to intersect the appropriate matrix velocity
or lithology curve and read the porosity value on the y-axis. For rock
mixtures such as limy sandstones or cherty dolomites, intermediate
matrix lines may be interpolated.
To use the weighted-average transform for an unconsolidated sand,
a lack-of-compaction correction (Bcp) must be made. Enter the chart
with the slowness time and intersect the appropriate compaction
correction line to read the porosity on the y-axis. If the compaction
correction is not known, it can be determined by working backward
from a nearby clean water sand for which the porosity is known.
Example: Consolidated Formation
Given:
Δt = 76 μs/ft in a consolidated formation with
vma = 18,000 ft/s.
Find:
Porosity and the formation lithology (sandstone,
dolomite, or limestone).
Answer:
15% porosity and consolidated sandstone.
Example: Unconsolidated Formation
Given:
Unconsolidated formation with Δt = 100 μs/ft in
a nearby water sand with a porosity of 28%.
Find:
Porosity of the formation for Δt = 110 μs/ft.
Answer:
Enter the chart with 100 μs/ft on the x-axis and move
vertically upward to intersect 28-p.u. porosity. This
intersection point indicates the correction factor curve
of 1.2. Use the 1.2 correction value to find the porosity for
the other slowness time. The porosity of an unconsolidated formation with Δt = 110 μs/ft is 34 p.u.
Lithology
vma (ft/s)
Δtma (μs/ft)
vma (m/s)
Δtma (μs/m)
Sandstone
18,000–19,500
55.5–51.3
5,486–5,944
182–168
Limestone
21,000–23,000
47.6–43.5
6,400–7,010
156–143
Dolomite
23,000–26,000
43.5–38.5
7,010–7,925
143–126
Por
continued on next page
211
Porosity—Wireline, LWD
Sonic Tool
Por-1
Porosity Evaluation—Open Hole
(customary, former Por-3)
vf = 5,300 ft/s
50
50
Time average
Field observation
1.1
40
40
1.2
1.3
Porosity,
φ (p.u.)
Q
e
Ca
lci
t
Do
lom
i
te
30
1.4
)
ne
to
s
e
(lim
ne
sto
d
n
sa
tz
r
ua
30
1.5
1.6
Bcp
20
Porosity,
φ (p.u.)
20
26
,
23 000
21 ,000
19 ,000
18 ,500
,00
0
vma (ft/s)
10
Por
0
30
40
50
60
70
10
80
90
Interval transit time, ∆t (µs/ft)
© Schlumberger
212
100
110
120
0
130
Porosity—Wireline, LWD
Sonic Tool
Por-2
Porosity Evaluation—Open Hole
(metric, former Por-3m)
vf = 1,615 m/s
50
50
Time average
Field observation
1.1
40
40
1.2
Do
l
ite
om
30
20
vma (m/s)
10
0
100
1.4
e
ton
ds
n
sa
rtz
a
Qu
30
1.5
1.6
Bcp
8
7,0 ,000
6
0
5, ,40 0
5,5 950 0
D
00
Ce
C ol
Qu men alci omit
te
e
a rt
t
z s ed q
an
u
ds artz
ton
e sand
sto
ne
Porosity,
φ (p.u.)
te
lci
a
C
1.3
Porosity,
φ (p.u.)
20
10
Por
0
150
200
250
300
350
400
Interval transit time, ∆t (µs/m)
© Schlumberger
Purpose
This chart is used similarly to Chart Por-1 with metric units.
213
Porosity—Wireline, LWD
Density Tool
Por-3
Porosity Determination—Open Hole
ρf (g/cm3)
(former Por-5)
1.0 0.9 0.8
ρ
ma
ρ
ma
=2
= 2 .87
(d
.83
olo
1.2
40
=2
mi
te
= 2 .71
)
(
ca
.68
lci
=2
te
.6 5
)
(q
ua
rtz
sa
nd
sto
ne
)
1.1
ρ
ma
ρ
ma
ρ
ma
30
Porosity,
φ (p.u.)
20
φ=
ρma – ρb
ρma – ρf
10
0
2.8
2.6
2.4
3
Bulk density, ρb (g/cm )
2.31
2.2
2.0
*Mark of Schlumberger
© Schlumberger
Por
Purpose
This chart is used to convert grain density (g/cm3) to density porosity.
Description
Values of log-derived bulk density (ρb) corrected for borehole size,
matrix density of the formation (ρma), and fluid density (ρf) are used
to determine the density porosity (ϕD) of the logged formation. The
ρf is the density of the fluid saturating the rock immediately surrounding the borehole—usually mud filtrate.
Enter the borehole-corrected value of ρb on the x-axis and move
vertically to intersect the appropriate matrix density curve. From the
intersection point move horizontally to the fluid density line. Follow
the porosity trend line to the porosity scale to read the formation
214
porosity as determined by the density tool. This porosity in combination with CNL* Compensated Neutron Log, sonic, or both values of
por­osity can help determine the rock type of the formation.
Example
Given:
Find:
Answer:
ρb = 2.31 g/cm3 (log reading corrected for borehole
effect), ρma = 2.71 g/cm3 (calcite mineral), and
ρf = 1.1 g/cm3 (salt mud).
Density porosity.
ϕD = 25 p.u.
Porosity—Wireline
APS* Near-to-Array (APLC) and Near-to-Far (FPLC) Logs
Epithermal Neutron Porosity Equivalence—Open Hole
Purpose
This chart is used for the apparent limestone porosity recorded by the
APS Accelerator Porosity Sonde or sidewall neutron porosity (SNP)
tool to provide the equivalent porosity in sandstone or dolomite formations. It can also be used to obtain the apparent limestone porosity (used for the various crossplot porosity charts) for a log recorded
in sandstone or dolomite porosity units.
The HPLC curve is the high-resolution version of the APLC curve.
The same corrections apply.
Description
Enter the x-axis with the corrected near-to-array apparent limestone
porosity (APLC) or near-to-far apparent limestone porosity (FPLC)
and move vertically to the appropriate lithology curve. Then read the
equivalent porosity on the y-axis. For APS porosity recorded in sandstone or dolomite porosity units enter that value on the y-axis and
move horizontally to the recorded lithology curve. Then read the
apparent limestone neutron porosity for that point on the x-axis.
The APLC is the epithermal short-spacing apparent limestone
neutron porosity from the near-to-array detectors. The log is automatically corrected for standoff during acquisition. Because it is
epithermal this measurement does not need environmental corrections for temperature or chlorine effect. However, corrections for
mud weight and actual borehole size should be applied (see Chart
Neu-10). The short spacing means that the effect of density and
therefore the lithology on this curve is minimal.
The FPLC is the epithermal long-spacing apparent limestone neutron porosity acquired from the near-to-far detectors. Because it is
epithermal this measurement does not need environmental corrections for temperature or chlorine effect. However, corrections for
mud weight and actual borehole size should be applied (see Chart
Neu-10). The long spacing means that the density and therefore
lithology effect on this curve is pronounced, as seen on Charts Por-13
and Por-14.
Resolution
Short Spacing
Long Spacing
Normal
APLC
Epithermal neutron porosity (ENPI)†
FPLC
Enhanced
HPLC
HNPI†
HFLC
†
Not formation-salinity corrected.
Example: Equivalent Porosity
Given:
APLC = 25 p.u. and FPLC = 25 p.u.
Find:
Porosity for sandstone and for dolomite.
Answer:
Sandstone porosity from APLC = 28.5 p.u. and sandstone
porosity from FPLC = 30 p.u.
Dolomite porosity = 24 and 20 p.u., respectively.
Example: Apparent Porosity
Given:
Clean sandstone porosity = 20 p.u.
Find:
Apparent limestone neutron porosity.
Answer:
Enter the y-axis at 20 p.u. and move horizontally to
the quartz sandstone matrix curves. Move vertically
from the points of intersection to the x-axis and read
the apparent limestone neutron porosity values.
APLC = 16.8 p.u. and FPLC = 14.5 p.u.
Por
continued on next page
215
Porosity—Wireline
APS* Near-to-Array (APLC) and Near-to-Far (FPLC) Logs
Por-4
Epithermal Neutron Porosity Equivalence—Open Hole
(former Por-13a)
40
APLC
FPLC
SNP
20
Qu
ar
tz
True porosity
for indicated
matrix material,
φ (p.u.)
sa
nd
sto
ne
30
ite
lc
Ca
)
ne
o
t
es
(lim
ite
lom
o
D
10
0
0
10
20
Apparent limestone neutron porosity, φSNPcor (p.u.)
Apparent limestone neutron porosity, φAPScor (p.u.)
*Mark of Schlumberger
© Schlumberger
Por
216
30
40
Porosity—Wireline
General
Thermal Neutron Tool
Por-5
Porosity Equivalence—Open Hole
(former Por-13b)
40
Formation salinity
0 ppm
250,000 ppm
TNPH
NPHI
True porosity
for indicated
matrix material,
φ (p.u.)
Qu
ar
tz
sa
nd
C
sto
ne
30
20
c
al
ite
n
to
es
m
(li
e)
ite
lom
o
D
10
0
0
10
20
30
40
Apparent limestone neutron porosity, φCNLcor (p.u.)
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to convert CNL* Compensated Neutron Log porosity
curves (TNPH or NPHI) from one lithology to another. It can also be
used to obtain the apparent limestone porosity (used for the various
crossplot porosity charts) from a log recorded in sandstone or dolomite
porosity units.
Description
To determine the porosity of either quartz sandstone or dolomite
enter the chart with the either the TNPH or NPHI corrected
apparent limestone neutron porosity (ϕCNLcor) on the x-axis. Move
vertically to intersect the appropriate curve and read the porosity
for quartz sandstone or dolomite on the y-axis. The chart has a
built-in salinity correction for TNPH values.
NPHI
Thermal neutron porosity (ratio method)
NPOR
Neutron porosity (environmentally corrected and enhanced
vertical resolution processed)
TNPH
Thermal neutron porosity (environmentally corrected)
Example
Given:
Find:
Answer:
Por
Quartz sandstone formation, TNPH = 18 p.u. (apparent
limestone neutron porosity), and formation salinity =
250,000 ppm.
Porosity in sandstone.
From the TNPH porosity reading of 18 p.u. on the x-axis,
project a vertical line to intersect the quartz sandstone
dashed red curve. From the y-axis, the porosity of the
sandstone is 24 p.u.
217
Porosity—Wireline
Thermal Neutron Tool—CNT-D and CNT-S 21⁄2-in. Tools
Por-6
Porosity Equivalence—Open Hole
40
20
Lim
es
to
ne
True porosity
for indicated
matrix material,
φ (p.u.)
Sa
nd
sto
ne
30
ite
om
l
Do
10
0
–10
0
10
20
Apparent limestone neutron porosity (p.u.)
Por
© Schlumberger
Purpose
This chart is used similarly to Chart Por-5 to convert 21⁄2-in. compensated neutron tool (CNT) porosity values (TNPH) from one lithology
to another. Fresh formation water is assumed.
218
30
40
Porosity—LWD
General
adnVISION475* 4.75-in. Azimuthal Density Neutron Tool
Por-7
Porosity Equivalence—Open Hole
40
35
30
ne
sto
d
n
e)
sa
ton
s
tr z
e
a
(lim
Qu
te
e
t
mi
lci Dolo
a
C
25
True porosity
for indicated
matrix material,
φ (p.u.)
20
15
10
5
0
–5
0
5
10
15
20
25
30
35
40
Corrected apparent limestone neutron porosity, φADNcor (p.u.)
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to determine the porosity of sandstone, limestone,
or dolomite from the corrected apparent limestone porosity measured
with the adnVISION475 4.75-in. tool.
Description
Enter the chart on the x-axis with the corrected apparent limestone
porosity from Chart Neu-31 to intersect the curve for the appropriate
formation material. Read the porosity on the y-axis.
219
Por
Porosity—LWD
adnVISION675* 6.75-in. Azimuthal Density Neutron Tool
Por-8
Porosity Equivalence—Open Hole
40
35
30
e
ton
ds
n
e)
sa
ton
s
tr z
e
a
lim
Qu
e(
t
i
ite
lc
Ca
lom
o
D
25
True porosity
for indicated
matrix material,
φ (p.u.)
20
15
10
5
0
–5
0
5
10
15
20
25
Corrected apparent limestone neutron porosity, φADNcor (p.u.)
*Mark of Schlumberger
© Schlumberger
Por
Purpose
Chart Por-8 is used similarly to Chart Por-7 for determining
porosity from the corrected apparent limestone porosity from
the adnVISION675 6.75-in. tool.
220
30
35
40
Porosity—LWD
adnVISION825* 8.25-in. Azimuthal Density Neutron Tool
Por-9
Porosity Equivalence—Open Hole
40
35
30
e
ton
ds
n
e
Sa
ton
s
e
te
Lim
mi
o
l
Do
25
True porosity
(p.u.)
20
15
10
5
0
–5
0
5
10
15
20
25
30
35
40
Corrected apparent limestone neutron porosity, φADNcor (p.u.)
*Mark of Schlumberger
© Schlumberger
Purpose
Chart Por-9 is used similarly to Chart Por-7 for determining
porosity from the corrected apparent limestone porosity from
the adnVISION825 8.25-in. tool.
Por
221
Porosity—LWD
EcoScope* 6.75-in. Integrated LWD Tool, BPHI Porosity
Por-10
Porosity Equivalence—Open Hole
40
35
30
e
ton
s
ne
nd
Sa
sto
e
ite
Lim lom
o
D
25
True porosity
for indicated
matrix material,
φ (p.u.)
20
15
10
5
0
–5
0
5
10
15
20
25
30
35
40
Corrected apparent limestone BPHI porosity (p.u.)
*Mark of Schlumberger
© Schlumberger
Por
Purpose
This chart is used to determine the porosity of sandstone, limestone,
or dolomite from the corrected apparent limestone BPHI porosity
measured with the EcoScope 6.75-in. LWD tool.
Use this chart only with EcoScope best thermal neutron porosity
(BPHI) measurements; use Chart Por-10a with EcoScope thermal
neutron porosity (TNPH) measurements.
222
Description
Enter the chart on the x-axis with the corrected apparent limestone
BPHI porosity from Chart Neu-43 or Neu-44 to intersect the curve for
the appropriate formation material. Read the porosity on the y-axis.
Porosity—LWD
EcoScope* 6.75-in. Integrated LWD Tool, TNPH Porosity
Por-10a
Porosity Equivalence—Open Hole
40
35
30
ne
to
s
nd
Sa
25
True porosity
for indicated
matrix material,
φ (p.u.)
ne
sto
e
te
Lim
mi
o
l
Do
20
15
10
5
0
–5
0
5
10
15
20
25
30
35
40
Corrected apparent limestone TNPH porosity (p.u.)
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to determine the porosity of sandstone, limestone,
or dolomite from the corrected apparent limestone TNPH porosity
measured with the EcoScope 6.75-in. LWD tool.
Use this chart only with EcoScope thermal neutron porosity
(TNPH) measurements; use Chart Por-10 with EcoScope best
thermal neutron porosity, average (BPHI) measurements.
Description
Enter the chart on the x-axis with the corrected apparent limestone
TNPH porosity from Chart Neu-45 or Neu-46 to intersect the curve for
the appropriate formation material. Read the porosity on the y-axis.
223
Por
Porosity—Wireline
CNL* Compensated Neutron Log and Litho-Density* Tool
(fresh water in invaded zone)
Porosity and Lithology—Open Hole
Purpose
This chart is used with the bulk density and apparent limestone
porosity from the CNL Compensated Neutron Log and Litho-Density
tools, respectively, to approximate the lithology and determine the
crossplot porosity.
Description
Enter the chart with the environmentally corrected apparent neutron limestone porosity on the x-axis and bulk density on the y-axis.
The intersection of the two values describes the crossplot porosity
and lithology.
If the point is on a lithology curve, that indicates that the formation is primarily that lithology. If the point is between the lithology
curves, then the formation is a mixture of those lithologies. The position of the point in relation to the two lithology curves as composition endpoints indicates the mineral percentages of the formation.
The porosity for a point between lithology curves is determined
by scaling the crossplot porosity by connecting similar numbers on
the two lithology curves (e.g., 20 on the quartz sandstone curve to
20 on the limestone curve). The scale line closest to the point represents the crossplot porosity.
Chart Por-12 is used for the same purpose as this chart for salt­
water-invaded zones.
Por
224
Example
Given:
Find:
Answer:
Corrected apparent neutron limestone porosity =
16.5 p.u. and bulk density = 2.38 g/cm3.
Crossplot porosity and lithology.
Crossplot porosity = 18 p.u. The lithology is approximately 40% quartz and 60% limestone.
Porosity—Wireline
General
CNL* Compensated Neutron Log and Litho-Density* Tool
(fresh water in invaded zone)
Por-11
(former CP-1e)
Porosity and Lithology—Open Hole
Liquid-Filled Borehole (ρf = 1.000 g/cm3 and Cf = 0 ppm)
1.9
45
2.0
40
Sulfur
Salt
35
Ap
pro
xim
cor gas ate
rec
tion
2.1
2.2
35
20
15
2.4
10
5
2.6
35
30
30
25
20
15
te
20
mi
o
l
Do
10
15
5
0
2.7
15
10
2.5
30
e
25
ton
s
nd
25
sa
tz
r
e)
a
Qu
ton
s
e
(lim
20
e
t
25
lci
Ca
40
35
30
y
sit
ro
o
P
2.3
Bulk
density,
ρb (g/cm3)
45
40
Density
porosity,
φD (p.u.)
(ρma = 2.71 g/cm3,
ρf = 1.0 g/cm3)
5
10
0
0
5
–5
2.8
0
–10
2.9
3.0
–15
Anhydrite
0
10
20
30
Por
40
Corrected apparent limestone neutron porosity, φCNLcor (p.u.)
*Mark of Schlumberger
© Schlumberger
225
Porosity—Wireline
General
CNL* Compensated Neutron Log and Litho-Density* Tool
(salt water in invaded zone)
Por-12
(former CP-11)
Porosity and Lithology—Open Hole
Liquid-filled borehole (ρf = 1.190 g/cm3 and Cf = 250,000 ppm)
1.9
45
2.0
Sulfur
Salt
2.1
2.2
40
Ap
pro
xim
cor gas ate
rec
tion
35
y
sit
ro
o
P
25
2.3
2.4
Bulk
density,
ρb (g/cm3)
15
10
2.5
10
5
2.6
5
0
2.7
40
40
35
30
ne
sto
d
n
25
sa
rtz
20
e)
a
Qu
ton
s
0
e
2
(lim
te
i
c
l
Ca
15
20
ite
lom
o
D
15
45 45
35
30
35
30
25
30
20
25
15
Density
porosity,
φD (p.u.)
(ρma = 2.71 g/cm3,
ρf = 1.19 g/cm3)
10
5
10
0
0
5
–5
2.8
0
–10
2.9
–15
3.0
Anhydrite
0
10
20
30
40
Corrected apparent limestone neutron porosity, φCNLcor (p.u.)
*Mark of Schlumberger
© Schlumberger
Por
Purpose
This chart is used similarly to Chart Por-11 with CNL Compensated
Neutron Log and Litho-Density values to approximate the lithology
and determine the crossplot porosity in the saltwater-invaded zone.
226
Example
Given:
Find:
Answer:
Corrected apparent neutron limestone porosity =
16.5 p.u. and bulk density = 2.38 g/cm3.
Crossplot porosity and lithology.
Crossplot porosity = 20 p.u. The lithology is approximately 55% quartz and 45% limestone.
Porosity—Wireline
General
APS* and Litho-Density* Tools
Por-13
Porosity and Lithology—Open Hole
(former CP-1g)
Liquid-Filled Borehole (ρf = 1.000 g/cm3 and Cf = 0 ppm)
1.9
45
APLC
FPLC
2.0
40
35 35
Ap
pro
xim
cor gas ate
rec
tion
2.1
2.2
30 30
ity
os
r
Po
2.3
20 20
15 15
2.4
Bulk density,
ρb (g/cm3)
2.5
10
55
2.6
2.7
10
35
40
35
30
15
10
0
5
00
2.9
3.0
15
25
40
35
5
00
5
2.8
15
10 10
30
e
n
o
t
ds
an 5
e)
s
2
ton 30
rtz
s
a
e
Qu
(lim
e
t
i
20
lc
Ca 25
25
ite
m
lo
Do
0
0
2
2
25
40
e
rit
yd
h
An
0
10
20
30
40
Corrected APS apparent limestone neutron porosity, φAPScor (p.u.)
*Mark of Schlumberger
© Schlumberger
Por
Purpose
This chart is used to determine the lithology and porosity from the
Litho-Density bulk density and APS Accelerator Porosity Sonde porosity
log curves (APLC or FPLC). This chart applies to boreholes filled
with freshwater drilling fluid; Chart Por-14 is used for saltwater fluids.
Description
Enter either the APLC or FPLC porosity on the x-axis and the bulk
density on the y-axis. Use the blue matrix curves for APLC porosity
values and the red curves for FPLC porosity values. Anhydrite plots
on separate curves. The gas correction direction is indicated for
formations containing gas. Move parallel to the blue correction line
if the APLC porosity is used or to the red correction line if the FPLC
porosity is used.
Example
Given:
Find:
Answer:
APLC porosity = 8 p.u. and bulk density = 2.2 g/cm3.
Approximate quartz sandstone porosity.
Enter at 8 p.u. on the x-axis and 2.2 g/cm3 on the y-axis
to find the intersection point is in the gas-in-formation
correction region. Because the APLC porosity value was
used, move parallel to the blue gas correction line until
the blue quartz sandstone curve is intersected at approximately 19 p.u.
227
Porosity—Wireline
General
APS* and Litho-Density* Tools (saltwater formation)
Por-14
Porosity and Lithology—Open Hole
(former CP-1h)
Liquid-Filled Borehole (ρf = 1.190 g/cm3 and Cf = 250,000 ppm)
1.9
APLC
FPLC
2.0
45 45
40 40
Ap
pro
xim
cor gas ate
rec
tion
2.1
2.2
35 35
ity
ros
o
P
25
30
e
n
sto
nd 25
a
)
zs
30
20 20
ne
art
sto
Qu 0
e
2
(lim 5
ite
2
25
c
l
a
te
i
C
15
lom
Do
0
20
2
2.3
2.4
Bulk density,
ρb (g/cm3)
15 15
10 10
2.5
10
55
2.6
2.7
15
5
00
10
0
5
2.8
30 30
35
35
25
45
40
40
40
35
30
15
10
5
00
2.9
e
rit
yd
h
An
3.0
0
10
20
30
40
Corrected APS apparent limestone neutron porosity, φAPScor (p.u.)
*Mark of Schlumberger
© Schlumberger
Por
Purpose
This chart is used similarly to Chart Por-13 to determine the lithology
and porosity from Litho-Density* bulk density and APS* porosity log
curves (APLC or FPLC) in saltwater boreholes.
228
Example
Given:
APLC porosity = 8 p.u. and bulk density = 2.2 g/cm3.
Find:
Approximate quartz sandstone porosity.
Answer:
Enter 8 p.u. on the x-axis and 2.2 g/cm3 on the y-axis
to find the intersection point is in the gas-in-formation
correction region. Because the APLC porosity value was
used, move parallel to the blue gas correction line until
the blue quartz sandstone curve is intersected at approximately 20 p.u.
Porosity—LWD
General
adnVISION475* 4.75-in. Azimuthal Density Neutron Tool
Por-15
Porosity and Lithology—Open Hole
Fresh Water, Liquid-Filled Borehole (ρf = 1.0 g/cm3)
1.9
Salt
40
2.0
ity
os
r
Po
2.1
30
35
25
2.3
20
15
2.4
15
10
2.5
10
5
2.6
30
15
5
0
2.7
40
35
30
e
ton
s
nd
sa
25
z
t
)
ar
ne
Qu
sto
e
lim
20
e(
t
i
25
lc
Ca
ite
om
l
o
20
D
2.2
Bulk density,
ρb (g/cm3)
35
40
10
0
5
2.8
0
2.9
Anhydrite
3.0
–5
0
5
10
15
20
25
30
35
40
45
Corrected apparent limestone neutron porosity, φADNcor (p.u.)
*Mark of Schlumberger
© Schlumberger
Por
Purpose
This chart is used to determine the crossplot porosity and lithology
from the adnVISION475 4.75-in. density and neutron porosity.
Description
Enter the chart with the adnVISION475 corrected apparent limestone neutron porosity (from Chart Neu-31) and bulk density. The
intersection of the two values is the crossplot porosity. The position
of the point of intersection between the matrix curves represents the
relative percentage of each matrix material.
Example
Given:
ϕADNcor = 20 p.u. and ρb = 2.24 g/cm3.
Find:
Answer:
Crossplot porosity and matrix material.
25 p.u. in sandstone.
229
Porosity—LWD
General
adnVISION675* 6.75-in. Azimuthal Density Neutron Tool
Por-16
Porosity and Lithology—Open Hole
Fresh Water, Liquid-Filled Borehole (ρf = 1.0 g/cm3)
1.9
40
2.0
2.1
y
30
sit
ro
o
P
30
25
e
n
sto
nd 25
a
s
e)
tz
20
ton
ar
s
u
e
Q
lim
20
e(
t
25
i
lc
Ca
2.2
2.3
Bulk density,
ρb (g/cm3)
15
2.4
20
10
5
2.7
15
10
2.5
2.6
40
35
35
35
30
te
mi
o
l
Do
15
5
0
10
0
5
2.8
0
2.9
3.0
–5
0
5
10
15
20
25
30
35
40
45
Corrected apparent limestone neutron porosity, φADNcor (p.u.)
Por
*Mark of Schlumberger
© Schlumberger
Purpose
This chart uses the bulk density and apparent limestone porosity from
the adnVISION 6.75-in. Azimuthal Density Neutron tool to determine
the lithology of the logged formation and the crossplot porosity.
Description
This chart is applicable for logs obtained in freshwater drilling
fluid. Enter the corrected apparent limestone porosity and the bulk
density on the x- and y-axis, respectively. Their intersection point
determines the lithology and crossplot porosity.
230
Example
Given:
Find:
Answer:
Corrected adnVISION675 apparent limestone porosity =
20 p.u. and bulk density = 2.3 g /cm3.
Porosity and lithology type.
Entering the chart at 20 p.u. on the x-axis and 2.3 g /cm3
on the y-axis corresponds to a crossplot porosity of
21.5 p.u. and formation comprising approximately
60% quartz sandstone and 40% limestone.
Porosity—LWD
General
adnVISION825* 8.25-in. Azimuthal Density Neutron Tool
Por-17
Porosity and Lithology—Open Hole
Fresh Water, Liquid-Filled Borehole (ρf = 1.0 g/cm3)
1.9
40
2.0
35
2.2
30
e
n
sto
nd 25
a
s
e)
tz
ton
ar
s
u
e
Q
lim
20
e(
t
i
lc
ite
Ca
lom
o
D
15
20
10
2.5
10
5
15
5
10
0
25
15
30
20
2.4
2.6
30
25
2.3
Bulk density,
ρb (g/cm3)
35
40
ity
ros
o
P
35
2.1
40
2.7
0
5
0
2.8
2.9
3.0
–5
0
5
10
15
20
25
30
35
40
45
Corrected apparent limestone neutron porosity, φADNcor (p.u.)
Por
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Por-15 to determine the lithology
and crossplot porosity from adnVISION825 8.25-in. Azimuthal Density
Neutron values.
231
Porosity—LWD
EcoScope* 6.75-in. Integrated LWD Tool
Por-18
Porosity and Lithology—Open Hole
Fresh Water, Liquid-Filled Borehole (lf = 1.0 g/cm3)
1.9
45
40
2.0
35
Salt
2.1
30
ne
sto 25
d
n
Sa
2.2
20
2.3
Bulk density,
lb (g/cm3)
2.7
20
10
5
2.6
15
10
2.5
40
35
30
35
25
30
ne
sto
e
25
Lim
20
15
2.4
40
te
mi
o
l
Do
15
5
0
10
0
5
2.8
0
2.9
3.0
–5
Anhydrite
0
5
10
15
20
25
30
Corrected apparent limestone BPHI porosity (p.u.)
*Mark of Schlumberger
© Schlumberger
Por
Purpose
This chart is used similarly to Chart Por-15 to determine the lithology and crossplot porosity from EcoScope 6.75-in. density and best
thermal neutron porosity (BPHI) values.
Use this chart only with EcoScope BPHI neutron porosity; use
Chart Por-19 with EcoScope thermal neutron porosity (TNPH)
measurements.
232
35
40
45
Porosity—LWD
EcoScope* 6.75-in. Integrated LWD Tool
Por-19
Porosity and Lithology—Open Hole
Fresh Water, Liquid-Filled Borehole (lf = 1.0 g/cm3)
1.9
45
40
40
2.0
35
Salt
2.1
30
2.2
2.3
Bulk density,
lb (g/cm3)
15
2.4
15
10
2.5
10
5
2.6
2.7
30
25
20
ne
sto
d
n
Sa 20
e
ton
s
e
Lim
35
25
40
35
30
25
20
ite
lom
o
D
15
5
0
10
0
5
2.8
0
2.9
3.0
–5
Anhydrite
0
5
10
15
20
25
30
35
40
45
Corrected apparent limestone TNPH porosity (p.u.)
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Por-15 to determine the lithology and crossplot porosity from EcoScope 6.75-in. density and thermal neutron porosity (TNPH) values.
Use this chart only with EcoScope TNPH neutron porosity; use
Chart Por-18 with EcoScope best thermal neutron porosity (BPHI)
measurements.
Por
233
Porosity—Wireline
General
Sonic and Thermal Neutron Crossplot
Porosity and Lithology—Open Hole, Freshwater Invaded
Purpose
This chart is used to determine crossplot porosity and an approxi­
mation of lithology for sonic and thermal neutron logs in freshwater
drilling fluid.
Example
Given:
Description
Enter the corrected neutron porosity (apparent limestone porosity)
on the x-axis and the sonic slowness time (Δt) on the y-axis to find
their intersection point, which describes the crossplot porosity and
lithology composition of the formation. Two sets of curves are drawn
on the chart. The blue set of curves represents the crossplot porosity
values using the sonic time-average algorithm. The red set of curves
represents the field observation algorithm.
Find:
Answer:
Por
234
Thermal neutron apparent limestone porosity = 20 p.u.
and sonic slowness time = 89 μs/ft in freshwater
drilling fluid.
Crossplot porosity and lithology.
Enter the neutron porosity on the x-axis and the sonic
slowness time on the y-axis. The intersection point is at
about 25 p.u. on the field observation line and 24.5 p.u.
on the time-average line. The matrix is quartz sandstone.
Porosity—Wireline
General
Sonic and Thermal Neutron Crossplot
Por-20
Porosity and Lithology—Open Hole, Freshwater Invaded
(customary, former CP-2c)
tf = 190 µs/ft and Cf = 0 ppm
110
35
40
40
Time average
Field observation
35 35
30
20
25
30
35
30
35
Qu
30 30
ar
tz
sa
nd
sto
ne
90
25 25
Po
ros
ity
100
15
15
Sonic transit time,
∆t (µs/ft)
30
15
10
10
20
5
60
15
10
5
10
Sa
lt
20
15
10
70
25
20
20
Ca
lci
t
20 e (lim
es
t
25 one
Do
)
lom
ite
25
80
15
Por
5
0
0
5
5
An
hy
dr
ite
0
50
10
0
5
0
0
40
0
10
20
30
40
Corrected CNL* apparent limestone neutron porosity, φCNLcor (p.u.)
*Mark of Schlumberger
© Schlumberger
235
Porosity—Wireline
General
Sonic and Thermal Neutron Crossplot
Por-21
Porosity and Lithology—Open Hole, Freshwater Invaded
(metric, former CP-2cm)
t f = 620 µs/m and Cf = 0 ppm
360
40
40
Time average
Field observation
15
25
10
20
5
200
15
10
5
10
15
Sa
lt
20
15
10
15
20
240
30
20
20
260
Sonic transit time,
∆t (µs/m)
Ca
lci
te
(
Do
25
25 lime
lom
sto
ne
ite
)
25
20
280
220
35
30
30
25
25
Po
ros
ity
300
35
320
35 35
Qu
30 30
ar
tz
sa
nd
sto
ne
30
35
340
10
5
5
160
15
5
0
Por
An
hy
dri
te
180
0
0
5
10
0
0
0
140
0
*Mark of Schlumberger
© Schlumberger
10
Purpose
This chart is used similarly to Chart Por-20 for metric units.
236
20
30
Corrected CNL* apparent limestone neutron porosity, φCNLcor (p.u.)
40
Porosity—Wireline, LWD
General
Density and Sonic Crossplot
Porosity and Lithology—Open Hole, Freshwater Invaded
Purpose
This chart is used to determine porosity and lithology for sonic and
density logs in freshwater-invaded zones.
Example
Given:
Description
Enter the chart with the bulk density on the y-axis and sonic slowness time on the x-axis. The point of intersection indicates the type
of formation and its porosity.
Find:
Answer:
Bulk density = 2.3 g /cm3 and sonic slowness
time = 82 μs/ft.
Crossplot porosity and lithology.
Limestone with a crossplot porosity = 24 p.u.
Por
continued on next page
237
Porosity—Wireline, LWD
General
Density and Sonic Crossplot
Por-22
Porosity and Lithology—Open Hole, Freshwater Invaded
(customary, former CP-7)
t f = 189 µs/ft and ρf = 1.0 g/cm3
1.8
Time average
Field observation
Sylvite
1.9
40
40
2.0
Salt
40
Sulfur
Trona
40
2.1
30
30
30
2.2
40
30
ity
os
r
Po
2.3
20
Gypsum
30
2.4
2.7
Por
2.8
2.9
3.0
40
20
10
10
10
Polyhalite
00
Do
lom
ite
2.6
0 Ca
Qu
ar
0 lcit
tz
e(
sa
lim
nd
es
sto
ton
ne
e)
10
0
0
10
10
2.5
20
Bulk density,
ρb (g/cm3)
20
20
20
30
Anhydrite
50
60
70
80
90
Sonic transit time, ∆t (µs/ft)
© Schlumberger
238
100
110
120
Porosity—Wireline, LWD
General
Density and Sonic Crossplot
Por-23
Porosity and Lithology—Open Hole, Freshwater Invaded
(metric, former CP-7m)
t f = 620 µs/m and ρf = 1.0 g/cm3
1.8
Time average
Field observation
Sylvite
1.9
40
40
2.0
Salt
2.1
Sulfur
30
40
Trona
30
30
2.2
40
30
y
sit
ro
o
P
2.3
30
20
20
20
20
30
Gypsum
2.4
2.7
2.8
2.9
3.0
Por
10
Polyhalite
0
0 Do
lom
ite
2.6
Qu
0 Ca
ar
0 lc
tz
ite
sa
(lim
nd
sto
es
ton
ne
e)
10
0
0
10
10
20
10
10
2.5
20
Bulk density,
ρb (g/cm3)
40
Anhydrite
150
200
© Schlumberger
250
300
350
400
Sonic transit time, ∆t (µs/m)
Purpose
This chart is used similarly to Chart Por-22 for metric units.
239
Porosity—Wireline, LWD
General
Density and Neutron Tool
Porosity Identification—Gas-Bearing Formation
Purpose
This chart is used to determine the porosity and average water
saturation in the flushed zone (Sxo) for freshwater invasion and gas
composition of C1.1H4.2 (natural gas).
Description
Enter the chart with the neutron- and density-derived porosity values
(ϕN and ϕD, respectively). On the basis of the table, use the blue curves
for shallow reservoirs and the red curves for deep reservoirs.
Example
Given:
Find:
Answer:
ϕD = 25 p.u. and ϕN = 10 p.u. in a low-pressure, shallow
(4,000-ft) reservoir.
Porosity and Sxo.
Enter the chart at 25 p.u. on the y-axis and 10 p.u. on the
x-axis. The point of intersection identifies (on the blue
curves for a shallow reservoir) ϕ = 20 p.u. and Sxo = 62%.
ρg (g/cm3)
Depth
Pressure
Temperature
ρw (g/cm3)
IHw
Shallow reservoir
~2,000 psi [~14,000 kPa]
~120°F [~50°C]
1.00
1.00
0
0
Deep reservoir
~7,000 psi [~48,000 kPa]
~240°F [~120°C]
1.00
1.00
0.25
0.54
ρw = density of water, ρg = density of gas, IHw = hydrogen index of water, and IHg = hydrogen index of gas
Por
240
IHg
Porosity—Wireline, LWD
General
Density and Neutron Tool
Por-24
Porosity Identification—Gas-Bearing Formation
(former CP-5)
50
40
0
20
35
40
35
Porosity
40
30
30
60
0
25
20
30
25
80
40
Density-derived porosity,
φD (p.u.)
20
20
100
Sxo
60
80
100
Sxo
20
15
10
15
10
10
5
0
0
For shallow reservoirs, use blue curves.
For deep reservoirs, use red curves.
5
10
20
30
Por
40
Neutron-derived porosity, φN (p.u.)
© Schlumberger
241
General
Porosity—Wireline
Density and APS* Epithermal Neutron Tool
Porosity Identification—Gas-Bearing Formation
Purpose
This chart is used to determine the porosity and average water
saturation in the flushed zone (Sxo) for freshwater invasion and gas
composition of CH4 (methane).
Description
Enter the chart with the APS Accelerator Porosity Sonde neutron- and
density-derived porosity values (ϕN and ϕD, respectively). On the basis
of the table, use the blue curves for shallow reservoirs and the red
curves for deep reservoirs.
Example
Given:
Find:
Answer:
ϕD = 15 p.u. and APS ϕN = 8 p.u. in a normally pressured
deep (14,000-ft) reservoir.
Porosity and S xo.
ϕ = 11 p.u. and S xo = 39%.
Depth
Pressure
Temperature
ρw
IHw
ρg
IHg
Shallow reservoir
~2,000 psi [~14,000 kPa]
~120°F [~50°C]
1.00
1.00
0.10
0.23
Deep reservoir
~7,000 psi [~48,000 kPa]
~240°F [~120°C]
1.00
1.00
0.25
0.54
ρw = density of water, ρg = density of gas, IHw = hydrogen index of water, and IHg = hydrogen index of gas
Por
242
Porosity—Wireline
General
Density and APS* Epithermal Neutron Tool
Por-25
Porosity Identification—Gas-Bearing Formation
(former CP-5a)
50
40
40
0
35
20
40
Porosity
40
30
35
30
60
80
25
25
0
30
20
100
40
60
Density-derived porosity,
φD (p.u.)
20
20
Sxo
80
100
Sxo
20
15 15
10
10
10
For shallow reservoirs, use blue curves.
For deep reservoirs, use red curves.
55
0
Por
0
10
20
30
40
APS epithermal neutron-derived porosity, φN (p.u.)
*Mark of Schlumberger
© Schlumberger
243
Porosity—Wireline
General
Density, Neutron, and Rxo Logs
Porosity Identification in Hydrocarbon-Bearing Formation—Open Hole
Purpose
This nomograph is used to estimate porosity in hydrocarbon-bearing
formations by using density, neutron, and resistivity in the flushed
zone (Rxo) logs. The density and neutron logs must be corrected for
environmental effects and lithology before entry to the nomograph.
The chart includes an approximate correction for excavation effect,
but if hydrocarbon density (ρh) is <0.25 g /cm3 (gas), the chart may
not be accurate in some extreme cases:
■
■
very high values of porosity (>35 p.u.) coupled with medium
to high values of hydrocarbon saturation (Shr)
Shr = 100% for medium to high values of porosity.
Description
Connect the apparent neutron porosity value on the appropriate
neutron porosity scale (CNL* Compensated Neutron Log or sidewall
neutron porosity [SNP] log) with the corrected apparent density
porosity on the density scale with a straight line. The intersection
point on the ϕ1 scale indicates the value of ϕ1.
Draw a line from the ϕ1 value to the origin (lower right corner)
of the chart for Δϕ versus Shr.
Enter the chart with Shr from (Shr = 1 – Sxo) and move vertically
upward to determine the porosity correction factor (Δϕ) at the intersection with the line from the ϕ1 scale.
This correction factor algebraically added to the porosity ϕ1 gives
the corrected porosity.
Por
244
Example
Given:
Find:
Answer:
Corrected CNL apparent neutron porosity = 12 p.u.,
corrected apparent density porosity = 38 p.u., and
Shr = 50%.
Hydrocarbon-corrected porosity.
Enter the 12-p.u. ϕcor value on the CNL scale. A line from
this value to 38 p.u. on the ϕDcor scale intersects the ϕ1
scale at 32.2 p.u. The intersection of a line from this
value to the graph origin and Shr = 50% is Δϕ = –1.6 p.u.
Hydrocarbon-corrected porosity: 32.2 – 1.6 = 30.6 p.u.
Porosity—Wireline
General
Density, Neutron, and Rxo Logs
Por-26
Porosity Identification in Hydrocarbon-Bearing Formation—Open Hole
φcor
(CNL*)
50
φcor
(SNP)
φ1
50
(former CP-9)
φDcor
50
50
(p.u.)
40
40
40
40
30
30
30
30
–5
20
20
20
20
–4
–3
∆φ
(p.u.)
10
10
10
10
–2
Por
–1
0
0
0
0
100
80
60
40
20
0
0
Shr (%)
*Mark of Schlumberger
© Schlumberger
245
Porosity—Wireline
General
Hydrocarbon Density Estimation
Por-27
(former CP-10)
1.0
ρh
0.8
0.8
0.7
φSNPcor
φDcor
0.6
0.6
0.5
0.4
0.4
0.3
0.2
0
0
0
20
40
0.2
0.1
60
80
100
Shr (%)
1.0
ρh
0.8
0.8
0.7
φCNLcor
φDcor
0.6
0.6
0.4
0.5
0.4
0.3
0.2
0
0
Por
0
20
*Mark of Schlumberger
© Schlumberger
Purpose
This chart is used to estimate the hydrocarbon density (ρh) within
a formation from corrected neutron and density porosity values.
Description
Enter the ratio of the sidewall neutron porosity (SNP) or
CNL* Compensated Neutron Log neutron porosity and density
porosity corrected for lithology and environmental effects
(ϕSNPcor or ϕCNLcor /ϕDcor, respectively) on the y-axis and the
246
40
0.1
60
0.2
80
100
Shr (%)
hydrocarbon saturation on the x-axis. The intersection point of the
two values defines the density of the hydrocarbon.
Example
Given:
Find:
Answer:
Corrected CNL porosity = 15 p.u., corrected density
porosity = 25 p.u., and Shr = 30% (residual hydrocarbon).
Hydrocarbon density.
Porosity ratio = 15/25 = 0.6. ρh = 0.29 g /cm3.
Saturation—Wireline, LWD
General
Porosity Versus Formation Resistivity Factor
SatOH-1
Open Hole
50
2.5
(former Por-1)
5
10
20
50
100
200
500
1,000
2,000
5,000
10,000
40
30
25
20
15
FR =
Porosity,
φ (p.u.)
10
9
8
7
6
1
φ2
m
Vugs or
spherical pores
5
FR =
4
0.62
φ2.15
FR =
1
φm
2.8
2.5
Fractures
2.2
3
1.8
2
FR =
0.81
φ2
2.0
1.6
1.4
1
2.5
5
10
20
50
100
200
500
1,000
2,000
5,000
10,000
Formation resistivity factor, FR
© Schlumberger
Purpose
This chart is used for a variety of conversions of the formation
resistivity factor (FR) to porosity.
Example
Given:
Description
The most appropriate conversion is best determined by laboratory
measurement or experience in the area. In the absence of this
knowledge, recommended relationships are the following:
Find:
Answer:
■
■
Soft formation with
ϕ = 25 p.u.
FR.
FR = 13 (from chart).
FR = 12.96 (calculated).
Hard formation (m = 2) with
ϕ = 8 p.u.
FR.
FR = 160 (from chart).
FR = 156 (calculated).
Soft formations (Humble formula): FR = 0.62/ϕ2.51 or Fr = 0.81/ϕ2
Hard formations: FR = 1/ϕm with the appropriate cementation factor (m).
247
SatOH
Saturation—Wireline, LWD
Spherical and Fracture Porosity
SatOH-2
Open Hole
(former Por-1a)
3.0
12.5
7.5
5.0
2.5
2.0
2.5
10.0
Isolated
pores
1.5
1.0
φiso = 0.5
Cementation
exponent, m
2.0
φ fr =
0.1
0.2
0.5
1.5
1.5
1.0
0.5
0.8
1
2
Fractures
1.0
2.0
2.5
4
6
Porosity, φ (p.u.)
5.0
8
.0
10
10
20
30
40
50
© Schlumberger
Purpose
This chart is used to identify how much of the measured porosity
is isolated (vugs or moldic) or fractured porosity.
SatOH Description
This chart is based on a simplified model that assumes no contribution to formation conductivity from vugs and moldic porosity and the
cementation exponent (m) of fractures is 1.0.
When the pores of a porous formation have an aspect ratio close
to 1 (vugs or moldic porosity), the value of m of the formation is usually greater than 2. Fractured formations typically have a cementation exponent less than 2.
248
Enter the chart with the porosity (ϕ) on the x-axis and m on the
y-axis. The intersection point gives an estimate of either the amount
of isolated porosity (ϕiso) or the amount of porosity resulting from
fractures (ϕfr).
Example
Given:
Find:
Answer:
ϕ = 10 p.u. and cementation exponent = 2.5.
Intergranular (matrix) porosity.
Entering the chart with 10 p.u. and 2.5 gives an intersection point of ϕiso = approximately 4.5 p.u.
Intergranular porosity = 10 – 4.5 = 5.5 p.u.
Saturation—Wireline, LWD
Saturation Determination
Open Hole
Purpose
This nomograph is used to solve the Archie water saturation
equation:
Sw =
Ro
FR
= R w,
Rt
Rt
where
Sw = water saturation
Ro = resistivity of clean-water formation
Rt = true resistivity of the formation
FR = formation resistivity factor
Rw = formation water resistivity.
It should be used in clean (nonshaly) formations only.
Description
If Ro is known, a straight line from the known Ro value through the
measured Rt value indicates the value of Sw. If Ro is unknown, it may
be determined by connecting Rw with FR or porosity (ϕ).
Example
Given:
Find:
Answer:
Rw = 0.05 ohm-m at formation temperature, ϕ = 20 p.u.
(FR = 25), and Rt = 10 ohm-m.
Water saturation.
Enter the nomograph on the Rw scale at Rw = 0.05 ohm-m.
Draw a straight line from 0.05 through the porosity scale
at 20 p.u. to intersect the Ro scale.
From the intersection point of R o = 1, draw a straight line
through Rt = 10 ohm-m to intersect the Sw scale.
Sw = 31.5%.
SatOH
continued on next page
249
Saturation—Wireline, LWD
Saturation Determination
SatOH-3
Open Hole
(former Sw-1)
Clean Formations, m = 2
Sw
(%)
Ro
(ohm-m)
Rw
(ohm-m)
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1.5
2
φ
(%)
FR
2.5
3
4
5
6
7
8
9
10
2,000
1,000
800
600
400
300
200
100
80
60
50
40
30
20
15
20
25
30
35
40
45
50
FR =
10
8
6
5
4
1
φ2.0
30
20
18
16
14
12
10
9
8
7
6
5
4
3
2
1.8
1.6
1.4
1.2
1.0
0.9
0.8
0.7
0.6
0.5
0.4
m = 2.0
0.3
0.2
0.18
0.16
0.14
0.12
0.10
Ro = FRRw
SatOH
© Schlumberger
250
Rt
(ohm-m)
10,000
8,000
6,000
5,000
4,000
3,000
2,000
5
6
7
8
9
1,000
800
600
500
400
300
200
10
11
12
13
14
15
16
100
80
60
50
40
30
20
18
20
10
8
6
5
4
3
2
1.0
0.8
0.6
0.5
0.4
0.3
0.2
0.1
25
30
40
50
60
70
80
90
100
Sw = Ro
Rt
Saturation—Wireline, LWD
Saturation Determination
Open Hole
Purpose
This chart is used to determine water saturation (Sw) in shaly or
clean formations when knowledge of the porosity is unavailable. It
may also be used to verify the water saturation determination from
another interpretation method. The large chart assumes that the
mud filtrate saturation is
Example
Given:
Find:
Answer:
S XO = 5 S W .
The small chart provides an Sxo correction when Sxo is known.
However, water activity correction is not provided for the SP portion
of the chart (see Chart SP-2).
Description
Clean Sands
Enter the large chart with the ratio of the resistivity of the flushed
zone to the true formation resistivity (Rxo /Rt) on the y-axis and the
ratio of the resistivity of the mud filtrate to the resistivity of the formation water (Rmf /Rw) on the x-axis to find the water saturation at
average residual oil saturation (Swa). If Rmf /Rw is unknown, the chart
may be entered with the spontaneous potential (SP) value and the
formation temperature. If Sxo is known, move diagonally upward,
parallel to the constant-Swa curves, to the right edge of the chart.
Then, move horizontally to the known Sxo (or residual oil saturation
[ROS], Sor) value to obtain the corrected value of Sw.
Rxo = 12 ohm-m, Rt = 2 ohm-m, Rmf /Rw = 20, and
Sor = 20%.
Sw (after correction for ROS).
Enter the large chart at Rxo /Rt = 12/2 = 6 on the
y-axis and Rmf /Rw = 20 on the x-axis. From the point of
intersection (labeled A), move diagonally to the right to
intersect the chart edge and directly across to enter the
small chart and intersect Sor = 20%.
Sw = 43%.
Description
Shaly Sands
Enter the chart with Rxo /Rt and the SP in the shaly sand (EPSP). The
point of intersection gives the Swa value. Draw a line from the chart’s
origin (the small circle located at Rxo /Rt = Rmf /Rm = 1) through this
point to intersect with the value of static spontaneous potential (ESSP)
to obtain a value of Rxo /Rt corrected for shaliness. This value of Rxo /
Rt versus Rmf /Rw is plotted to find Sw if Rmf /Rw is unknown because
the point defined by Rxo /Rt and ESSP is a reasonable approximation
of Sw. The small chart to the right can be used to further refine Sw if
Sor is known.
Example
Given:
Rxo /Rt = 2.8, Rmf /Rw = 25, EPSP = –75 mV, ESSP = –120 mV,
and electrochemical SP coefficient (Kc) = 80 (formation
temperature = 150ºF).
Find:
Sw and corrected value for Sor = 10%.
Answer:
Enter the large chart at Rxo/Rt = 2.8 and the intersection
of EPSP = –75 mV at Kc = 80 from the chart below. A line
from the origin through the intersection point (labeled B)
intersects the –120-mV value of ESSP at Point C. Move
horizontally to the left to intersect Rmf /Rw = 25 at Point D.
Then move diagonally to the right to intersect the right
y-axis of the chart. Move horizontally to the small chart to
determine Sxo = 0.9%, Sw = 38%, and corrected Sw = 40%.
For more information, see Reference 12.
SatOH
continued on next page
251
Saturation—Wireline, LWD
Saturation Determination
SatOH-4
Open Hole
(former Sw-2)
Sor (%)
Rmf /Rw
0.6
0.8 1.0
1.5
2 2.5 3
4
5 6
0
8 10
15
20 25 30
50
EPSP = –Kc log
5
Sxo = S w
40
50
Sw
0%
10
=
a
6
5
A
50 60% 70%
%
3
25
15
20
B
15
3
25
% 0%
1
0.8
10
1.0
20
%
0.6
0.5
0.9
0.8
15
%
10
%
0.2
Sxo = 5 S w
0.1
0.08
0.6
0.8 1.0
1.5
2 2.5 3
4
Kc
70
75
100
Temperature 150
(°F)
200
5 6
8 10
Rmf /Rw
20 10
0
–20
–40
–60
–80
–100
EPSP or ESSP (mV)
252
15
20 25 30
80
90
100
0.7
Sxo
Sw = Sxo (Swa)0.8
0.4
0.3
20
C
D
40
%
2
25
30
Sw
4
© Schlumberger
(%)
30
40
8
300
40
50
60
Rxo
Sxo
– 2Kc log
Rt
Sw
10
SatOH
30
60
70
30
Rxo
Rt
20
80
40
20
10
40 50 60
–120
–140
40 50 60
25
50
75
100
150
Temperature
(°C)
0.6
Saturation—Wireline, LWD
Graphical Determination of Sw from Swt and Swb
SatOH-5
Open Hole
(former Sw-14)
100
Swb
90
70%
80
60%
50%
70
40%
30%
60
20%
10%
Swt (%)
0
50
40
30
20
10
0
0
10
20
30
40
50
60
70
80
90
100
Sw (%)
© Schlumberger
Purpose
This chart is used to drive a value of water saturation (Sw) corrected
for the bound-water volume in shale.
Description
This is a graphical determination of Sw from the total water saturation (Swt) and the saturation of bound water (Swb):
Sw =
SatOH
Enter the y-axis with Swt and move horizontally to intersect
the appropriate Swb curve. Read the value of Sw on the x-axis.
Example
Given:
Find:
Answer:
Swt = 45% and Swb = 10%.
Sw.
Sw = 39.5%.
S wt − S wb
.
1 − S wb
253
Saturation—Wireline, LWD
Porosity and Gas Saturation in Empty Hole
SatOH-6
Open Hole
(former Sw-11)
Density and Hydrogen Index of Gas Assumed Zero
Use if no
shale present
0
Use if no
oil present
Porosity, φ (p.u.)
2
4
6
8
10
12
14
16
18
20
22
24
26
28 30
100
2
90
4
6
80
8
70
10
12
70
60
50
60
(%)
14
50
16
18
40
30
22
24
20
20
26
15
14
13
12
11
10
28
30
0
2.6
2.5
2.4
2.3
2.2
2.1
2.0
1.9
1.8
2.70
Matrix density,
ρma (g/cm3)
2.80
Dolomite
2.90
2.8
2.7
2.6
2.5
2.4
2.3
2.2
2.1
2.0
1.9
Apparent bulk density from density log, ρb (g/cm3)
Purpose
This chart is used to determine porosity (ϕ) and gas saturation (Sg)
from the combination of density and neutron or from density and
SatOH resistivity measurements.
Description
Enter from the point of intersection of the matrix density (ρma)
and apparent bulk density (ρb). Move vertically upward to intersect
either neutron porosity (ϕN, corrected for lithology) or the ratio of
true resistivity to connate water resistivity (R t /Rw). This point defines
the actual porosity and Sg on the curves.
Oil saturation (So) can also be determined if all three measurements (density, neutron, and resistivity) are available. Find the values
of ϕ and Sg as before, and then find the intersection of R t /R w with ϕ
to read the value of the total hydrocarbon saturation (Sh) on the
saturation scale for use in the following equations:
254
Sandstone
Limy sandstone
Limestone
2.75
2.85
© Schlumberger
Rt
Rw
30
40
20
2.65
100
Gas
sat
ura
tion
, Sg
Neutron
porosity
index
(corrected
for lithology)
10,000
4,000
2,000
1,000
400
300
200
150
So = Sh – Sg
Sw = 100 – Sh.
Example
Given:
Find:
Answer:
Limy sandstone (ρma = 2.68 g /cm3), ρb = 2.44 g /cm3,
ϕN = 9 p.u., R t = 74 ohm-m, and R w = 0.1 ohm-m.
ϕ, Sg, Sh, So, and Sw.
First, find R t /R w = 74/0.1 = 740.
ϕ = 12 p.u. and Sg = 25%.
Sh = 70% (total hydrocarbon saturation).
So = 70 – 25 = 45%.
Sw = 100 – 70 = 30%.
Saturation—Wireline
EPT* Propagation Time
SatOH-7
Open Hole
7
(former Sxo-1)
tpma (ns/m)
8
9
10
7
tpma (ns/m)
8
9
10
Sxo
(%)
21
100
20
19
90
18
17
80
Gas il
O
16
15
13
11
10
9
8
/m)
(ns
70
10
5
15
20
60
30
50
4
40 5
35
30
25
53%
50
35
40
50
Fo
rm
ati
on
(% poro
)
sit
y
12
10.9
t pw
25
14
tpl (ns/m)
21
60
70
80
90
40
30
20
7
10
6
5
Sandstone
0
Limestone
Sandstone
Dolomite
Limestone
Dolomite
*Mark of Schlumberger
© Schlumberger
Purpose
This nomograph is used to define flushed zone saturation (Sxo) in
the rock immediately adjacent to the borehole by using the EPT
Electromagnetic Propagation Tool time measurement (tpl).
Description
Use of this chart requires knowledge of the reservoir lithology or
matrix propagation time (tpma), saturating water propagation time
(tpw), porosity (ϕ), and expected hydrocarbon type. Enter the far-left
scale with tpl and move parallel to the diagonal lines to intersect the
appropriate tpma value. From this point move horizontally to the right
edge of the scale grid. From this point, extend a straight line through
the porosity scale to the center scale grid; again, move parallel to the
diagonal lines to the appropriate tpma value and then horizontally to
the right edge of the grid scale. From this point, extend a straight
line through the intersection of tpw and the hydrocarbon type point
SatOH
to intersect the Sxo scale. For more information, see Reference 25.
255
Saturation—Wireline
EPT* Attenuation
SatOH-8
Open Hole
(former Sxo-2)
Sxo
(%)
5
6
Aw
(dB/m)
7
6,000
8
9
10
AEPTcor
(dB/m)
5,000
4,000
1
3,000
2,000
2
φ
(p.u.)
6
8
2
1,000
900
800
700
600
500
20
3
4
1
30
3
4
5
10
10
30
40
400
15
20
300
30
40
40
20
60
80
100
200
50
60
70
80
90
100
200
300
400
*Mark of Schlumberger
© Schlumberger
Purpose
This nomograph is used to determine the flushed zone saturation
(Sxo) in the rock immediately adjacent to the borehole by using the
EPT Electromagnetic Propagation Tool attenuation measurement.
It requires knowledge of the saturating fluid (usually mud filtrate)
SatOH
attenuation (Aw), porosity (ϕ), and the EPT EATT attenuation
(AEPTcor) corrected for spreading loss.
Description
The value of Aw must first be determined. Chart Gen-16 is used to
estimate Aw by using the equivalent water salinity and formation
temperature. EPT-D spreading loss is determined from the inset on
Chart Gen-16 based on the uncorrected EPT propagation time (tpl)
measurement. The spreading loss correction algebraically added to
the EPT-D EATT attenuation measurement gives the corrected EPT
attenuation (AEPTcor). These values are used with porosity on the
nomograph to determine Sxo.
256
600
800
1,000
100
90
80
Example
Given:
Find:
Answer:
EATT = 250 dB/m, tpl = 10.9 ns/m, ϕ = 28 p.u., water salinity = 20,000 ppm, and bottomhole temperature = 150ºF.
Spreading loss (from Chart Gen-16 inset) and Sxo.
The spreading loss determined from the inset on
Chart Gen-16 is –82 dB/m.
AEPTcor = 250 – 82 = 168 dB/m.
Aw (from Chart Gen-16) = 1,100 dB/m.
Enter the far-left scale at Aw = 1,100 dB/m and draw
a straight line through ϕ = 28 p.u. on the next scale to
intersect the median line. From this intersection point,
draw a straight line through AEPTcor = 168 dB/m on the
next scale to intersect the Sxo value on the far-right
scale. Sxo = 56 p.u.
Saturation—Wireline
Capture Cross Section Tool
Cased Hole
Purpose
This chart is used to determine water saturation (Sw) from capture
cross section, or sigma (Σ), measurements from the TDT* Thermal
Decay Time pulsed neutron log.
Description
This chart uses sigma water (Σw), matrix capture cross section (Σma),
and porosity (ϕ) to determine water saturation in clean formations.
The chart may be used in shaly formations if sigma shale (Σsh), the
volume fraction of shale in the formation (Vsh), and the porosity corrected for shale are known.
Thermal decay time (t and tsh in shale) is also shown on some
of the chart scales because it is related to Σ.
Procedure
Clean Formation
The Sw determination for a clean formation requires values known
for Σma (based on lithology), ϕ, Σw from the NaCl salinity (see Chart
Gen-12 or Gen-13), and sigma hydrocarbon (Σh) (see Chart Gen-14).
Enter the value of Σma on Scale B and draw a line to Pivot Point B.
Enter Σlog on Scale B and draw Line b through the intersection of
Line a and the value of ϕ to intersect the sigma of the formation
fluid (Σf) on Scale C. Draw Line 5 from Σf through the intersection of
Σh and Σw to determine the value of Sw on Scale D.
Example: Clean Formation
Given:
Σlog = 20 c.u., Σma = 8 c.u. (sandstone) from TDT tool,
Σh = 18 c.u., Σw = 80 c.u. (150,000 ppm or mg/kg), and
ϕ = 30 p.u.
Find:
Sw.
Answer:
Following the procedure for a clean formation, Sw = 43%.
Procedure
Shaly Formation
The Sw determination in a shaly formation requires additional information: sigma shale (Σsh) read from the TDT log in adjacent shale,
Vsh from porosity-log crossplot or gamma ray, shale porosity (ϕsh) read
from a porosity log in adjacent shale, and the porosity corrected for
shaliness (ϕshcor) with the relation for neutron and density logs
in liquid-filled formations of ϕshcor = ϕlog – Vshϕsh.
Enter the value of Σma on Scale B and draw Line 1 to intersect
with Pivot Point A. From the value of Σsh on Scale A, draw Line 2
through the intersection of Line 1 and Vsh to determine the shalecorrected Σcor on Scale B. Draw Line 3 from Σcor to the value of Σma
on the scale to the left of Scale C. Enter Σlog on Scale B and draw
Line 4 through the intersection of Line 3 and the value of ϕ to determine Σf on Scale C. From Σf on Scale C, draw Line 5 through the
intersection of Σh and Σw to determine Sw on Scale D.
Example
Given:
Find:
Answer:
Σlog = 25 c.u.
Σma = 8 c.u.
Σh = 18 c.u.
Σw = 80 c.u.
Σsh = 45 c.u.
ϕlog = 33 p.u.
ϕsh = 45 p.u.
Vsh = 0.2.
ϕshcor and Sw.
First find the porosity corrected for shaliness,
ϕshcor = 33 p.u. – (0.2 × 45 p.u.) = 24 p.u. This value
is used for the ϕ point between Scales B and C.
Sw = 43%.
SatCH
continued on next page
257
Saturation—Wireline
Capture Cross Section Tool
SatCH-1
Cased Hole
(former Sw-12)
sh
A
20
30
200
(c.u.)
sh
40
150
120
50
100
60
90
80
t sh ( s)
2
Pivot point A
1
0.5
(c.u.)
B
0.4
0.3
0.2
50
40
30
100
120
140
20
160
200
300
400
5
t ( s)
10
15
45
a
0
f
5 10 15 20
30
30
40
40
50
50
60
60
70
80
Formation water
salinity (ppm 1,000)
0
20
0
25
(c.u.)
70
90
10
0
20
40
60
C
Pivot point B
3
(c.u.)
p.u.
80
90
100
110
120
120
0
10
15
21
ma
25
30
35
40
20
b
4
h
(c.u.)
5
SatCH
Sw (%)
100
90
80
70
60
50
40
30
20
D
Sw =
© Schlumberger
258
(
–
)– (
h
(
–
w
–
)–
h)
sh
(
sh
–
ma
0.1
10 0
cor
)
10
0
Saturation—Wireline
Capture Cross Section Tool
Cased Hole
Purpose
This chart is used to graphically interpret the TDT* Thermal Decay
Time log. In one technique, applicable in shaly as well as clean
sands, the apparent water capture cross ­section (Σwa) is plotted
versus bound-water saturation (Swb) on a ­specially constructed grid to
determine the total water saturation (Swt).
90
Description
To construct the grid, refer to the example chart on this page. Three
fluid points must be located: free-water point (Σwf), hydrocarbon
point (Σh), and a bound-water point (Σwb). The free- (or connate formation) water point is ­located on the left y-axis and can be obtained
from measurement of a formation water sample, from Charts Gen-12
and Gen-13 if the water salinity is known, or from the TDT log in
a clean water-bearing sand by using the following equation:
65
∑ wa =
∑ log − ∑ ma
φ
Example
Given:
Find:
Answer:
Bound-water
point
wb = 76
80
75
100% water line
70
60
+ ∑ ma .
(1)
S wt − S vb
.
1 − S wb
70
60
50
4
40
S
w
b
50
=
30
w
t
45
S
wa
80
7
5
6
8
55
(c.u.)
90%
Free-water
point
wf = 61
20
40
3
10
2
35
0
1
30
25
The hydrocarbon point is also located on the left y-axis of the grid.
It can be determined from Chart Gen-14 based on the known or
expected hydrocarbon type.
The bound-water point (Swb) can be obtained from the TDT log
in shale intervals also by using the Σwa equation. It is located on the
right y-axis of the grid.
The distance between the free-water and hydrocarbon points is
linearly divided into lines of constant water saturation drawn ­parallel
to a straight line connecting the free-water and bound-water points.
The Swt = 0% line originates from the hydrocarbon point, and the
Swt = 100% line originates from the free-water point.
The value of Σwa from the equation is plotted versus Swb to give
Swt. The value of Swb can be estimated from the gamma ray or other
bound-water saturation estimator.
Once Swt and Swb are known, the water saturation of the reservoir
rock exclusive of shale can be determined using
Sw =
85
(2)
Σwf = 61 c.u. and Σh = 21 c.u. (medium-gravity oil with
modest GOR from Chart Gen-14), and Σwb = 76 c.u.
(from TDT log in a shale interval and the preceding Eq. 1).
Swt and Sw for Point 4.
Σwa = 54 c.u. (from Eq. 1) and Swb = 25% (from
gamma ray).
Swt = 72% and Sw = 63% (from the preceding Sw
equation).
20
Hydrocarbon
point
h = 21
15
10
5
0
20
40
44 48 52
40
60
Swb (%)
80
56 60 64 68 72 76
Gamma Ray
(gAPI)
100
80
*Mark of Schlumberger
© Schlumberger
The grid can also be used to graphically determine water
s­ aturation (Sw) in clean formations by crossplotting Σlog on the
y-axis and porosity (ϕ) on the x-axis. The values of Σma and Sw need
not be known but must be constant over the interval ­studied. There
must be some points from 100% water zones and a good variation in
porosity. These water points define the Sw = 100% line; when extrapolated, this line intersects the zero-porosity axis at Σma. The Sw = 0%
line is drawn from Σma at ϕ = 0 p.u. to Σ = Σh at ϕ = 100 p.u. (or
Σ = 1⁄2(Σma + Σh) at ϕ = 50 p.u.). The vertical distance from Sw = 0%
to Sw = 100% is divided linearly to define lines of constant water
saturation. The water saturation of any plotted point can thereby
be determined.
continued on next page
259
SatCH
Saturation—Wireline
Capture Cross Section Tool
SatCH-2
Cased Hole
(former Sw-17)
log
or
wa
*Mark of Schlumberger
© Schlumberger
or Swb
SatCH
© Schlumberger
260
Saturation—Wireline
RSTPro* Reservoir Saturation Tool—1.6875 in. and 2.5 in.
Carbon/Oxygen Ratio—Open Hole
Purpose
Charts SatCH-3 through SatCH-8 are presented for illustrative
purposes only. They are used to ensure that the measured near- and
far-detector carbon/oxygen (C/O) ratio data are consistent with the
interpretation model. These example charts are drawn for specific
cased and open holes and tool sizes to provide trapezoids for the
to determination of oil saturation (So) and oil holdup (yo).
Description
Known formation and borehole data define the expected C/O ratio
values, which are determined in water saturation and borehole
holdup values ranging from 0 to 1. All log data for formations with
porosity (ϕ) greater than 10 p.u. should be within the trapezoidal
area bounded by the limits of the So and yo values. If data plot
consistently outside the trapezoid, the interpretation model may
require revision.
The rectangle within each chart is constructed from four distinct
points determined by the intersection of the near- and far-detector
C/O ratios:
WW = water/water point
WO = water/oil point
OW = oil/water point
OO = oil/oil point.
The oil used for both the formation and borehole is #2 diesel fuel
with a carbon density value (CDV) of 0.7313-g carbon per cm3 fuel.
RSTPro Reservoir Saturation Tool processing then determines the
water saturation (Sw) of the formation.
SatCH
continued on next page
261
Saturation—Wireline
RSTPro* Reservoir Saturation Tool—1.6875 in. and 2.5 in. in 6.125-in. Borehole,
#2 Diesel CDV = 0.7313-g Carbon per cm3
SatCH-3
(former RST-3)
Carbon/Oxygen Ratio—Open Hole
φ = 30%, 6.125-in. Open Hole
0.8
RST-A and RST-C, limestone
RST-A, quartz sandstone
RST-B and RST-D, limestone
RST-B, quartz sandstone
OO
0.6
Far-detector
carbon/oxygen
ratio
OO
OO
WO
0.4
OO
OW
WO
WO
0.2
OW
WO
WW
0
OW
WW
OW
WW
WW
0.5
Near-detector carbon/oxygen ratio
0
1.0
φ = 20%, 6.125-in. Open Hole
0.8
RST-A and RST-C, limestone
RST-A, quartz sandstone
RST-B and RST-D, limestone
RST-B, quartz sandstone
OO
0.6
Far-detector
carbon/oxygen
ratio
WO
WW
0.2
SatCH
0
OO
OW
0.4
WO
WO
WW
0
OO
WO
OW
OW
OW
WW
WW
0.5
Near-detector carbon/oxygen ratio
*Mark of Schlumberger
© Schlumberger
262
OO
1.0
Saturation—Wireline
RSTPro* Reservoir Saturation Tool—1.6875 in. and 2.5 in. in 9.875-in. Borehole,
#2 Diesel CDV = 0.7313-g Carbon per cm3
SatCH-4
Carbon/Oxygen Ratio—Open Hole
φ = 30%, 9.875-in. Open Hole
1.5
RST-A and RST-C, limestone
RST-A, quartz sandstone
RST-B and RST-D, limestone
RST-B, quartz sandstone
OO
1.0
OO
Far-detector
carbon/oxygen
ratio
OW
0.5
OW
WO
WO
WW
0
OW
WO
OW
WW
WW WW
0
0.5
1.5
1.0
Near-detector carbon/oxygen ratio
φ = 20%, 9.875-in. Open Hole
1.5
RST-A and RST-C, limestone
RST-A, quartz sandstone
RST-Band RST-D, limestone
RST-B, quartz sandstone
1.0
OO
Far-detector
carbon/oxygen
ratio
OW
OO
0.5
OW
OW
WO
0
WW
WO
WW
WO
OW
SatCH
WW
WW
0
0.5
1.0
1.5
Near-detector carbon/oxygen ratio
*Mark of Schlumberger
© Schlumberger
263
Saturation—Wireline
RSTPro* Reservoir Saturation Tool—1.6875 in. and 2.5 in. in 6.125-in. Borehole
with 4.5-in. Casing at 11.6 lbm/ft, #2 Diesel CDV = 0.7313-g Carbon per cm3
SatCH-5
(former RST-5)
Carbon/Oxygen Ratio—Cased Hole
φ = 30%, 6.125-in. Borehole, 4.5-in. Casing at 11.6 lbm/ft
0.8
RST-A and RST-C, limestone
RST-A, quartz sandstone
RST-B and RST-D, limestone
RST-B, quartz sandstone
0.6
Far-detector
carbon/oxygen
ratio
OO
OO
0.4
WO
WO
OW
WO
0.2
WW
WO
0
OO
OW
OO
OW
OW
WW WW
0.5
0
1.0
Near-detector carbon/oxygen ratio
φ = 20%, 6.125-in. Borehole, 4.5-in. Casing at 11.6 lbm/ft
0.8
RST-A and RST-C, limestone
RST-A, quartz sandstone
RST-B and RST-D, limestone
RST-B, quartz sandstone
0.6
Far-detector
carbon/oxygen
ratio
OO
0.4
WO
WO
0.2
WO
WO
SatCH
0
WW
264
WW
WW
OO
OW
OO
OW
OW
WW
0
*Mark of Schlumberger
© Schlumberger
OO
OW
0.5
Near-detector carbon/oxygen ratio
1.0
Saturation—Wireline
RSTPro* Reservoir Saturation Tool—1.6875 in. and 2.5 in. in 7.875-in. Borehole
with 5.5-in. Casing at 17 lbm/ft, #2 Diesel CDV = 0.7313-g Carbon per cm3
SatCH-6
Carbon/Oxygen Ratio—Cased Hole
φ = 30%, 7.875-in. Borehole, 5.5-in. Casing at 17 lbm/ft
0.8
RST-A and RST-C, limestone
RST-A, quartz sandstone
RST-B and RST-D, limestone
RST-B, quartz sandstone
OO
0.6
Far-detector
carbon/oxygen
ratio
OO
OW
0.4
OO
WO
WO
0.2
0
WO
WO
WW
OO
OW
OW
WW
OW
WW
WW
0.5
0
1.0
Near-detector carbon/oxygen ratio
φ = 20%, 7.875-in. Borehole, 5.5-in. Casing at 17 lbm/ft
0.8
RST-A and RST-C, limestone
RST-A, quartz sandstone
RST-B and RST-D, limestone
RST-B, quartz sandstone
0.6
Far-detector
carbon/oxygen
ratio
OO
OW
0.4
0.2
0
WO
WO
WW
WW
WO
WO
WW
WW
0
OO
OO
OW
OO
OW
OW
0.5
Near-detector carbon/oxygen ratio
SatCH
1.0
*Mark of Schlumberger
© Schlumberger
265
Saturation—Wireline
RSTPro* Reservoir Saturation Tool—1.6875 in. and 2.5 in. in 8.5-in. Borehole
with 7-in. Casing at 29 lbm/ft, #2 Diesel CDV = 0.7313-g Carbon per cm3
SatCH-7
(former RST-1)
Carbon/Oxygen Ratio—Cased Hole
φ = 30%, 8.5-in. Borehole, 7-in. Casing at 29 lbm/ft
RST-A and RST-C, limestone
RST-A, quartz sandstone
RST-B and RST-D, limestone
RST-B, quartz sandstone
0.8
OO
0.6
Far-detector
carbon/oxygen
ratio
OO
OW
0.4
OO
OO
OW
WO
OW
WO
0.2
WO
0
OW
WW
WW
WW
0.5
0
1.0
Near-detector carbon/oxygen ratio
φ = 20%, 8.5-in. Borehole, 7-in. Casing at 29 lbm/ft
RST-A and RST-C, limestone
RST-A, quartz sandstone
RST-B and RST-D, limestone
RST-B, quartz sandstone
0.8
OO
0.6
OW
Far-detector
carbon/oxygen
ratio
OO
OO
OW
0.4
OW
OO
WO
0.2
SatCH
0
WW
WO
266
OW
WW
WW
WW
0
*Mark of Schlumberger
© Schlumberger
WO
0.5
Near-detector carbon/oxygen ratio
1.0
Saturation—Wireline
RSTPro* Reservoir Saturation Tool—1.6875 in. and 2.5 in. in 9.875-in. Borehole
with 7-in. Casing at 29 lbm/ft, #2 Diesel CDV = 0.7313-g Carbon per cm3
SatCH-8
(former RST-2)
Carbon/Oxygen Ratio—Cased Hole
φ = 30%, 9.875-in. Borehole, 7-in. Casing at 29 lbm/ft
0.8
RST-A and RST-C, limestone
RST-A, quartz sandstone
RST-B and RST-D, limestone
RST-B, quartz sandstone
OO
0.6
OO
OW
Far-detector
carbon/oxygen
ratio
0.4
OW
OO
WO
0.2
0
OO
OW
WO
WO
WO
WW
WW
WW
OW
WW
0.5
0
1.0
Near-detector carbon/oxygen ratio
φ = 20%, 9.875-in. Borehole, 7-in. Casing at 29 lbm/ft
0.8
RST-A and RST-C, limestone
RST-A, quartz sandstone
RST-B and RST-D, limestone
RST-B, quartz sandstone
OO
0.6
Far-detector
carbon/oxygen
ratio
OW
OO
OW
0.4
OO
OW
0.2
0
OO
WO
WO
WW WO
WO
WW
WW
OW
SatCH
WW
0
0.5
Near-detector carbon/oxygen ratio
1.0
*Mark of Schlumberger
© Schlumberger
267
General
Permeability
Permeability from Porosity and Water Saturation
Open Hole
Purpose
Charts Perm-1 and Perm-2 are used to estimate the permeability of
shales, shaly sands, or other hydrocarbon-saturated intergranular
rocks at irreducible water saturation (Swi).
Description
The charts are based on empirical observations and are similar in
form to a general expression proposed by Wyllie and Rose (1950)
(see Reference 49):
 Cφ 
k 1/ 2 = 
 + C ′.
 S wi 
Example
Given:
Find:
Answer:
pc =
(2)
(
h ρ w − ρh
2.3
).
2.0
pc = 200
1.8
1.6
Correction
factor, C′
h(ρw – ρo)
2.3
1.4
pc = 100
(4)
pc = 40
pc = 10
pc = 0
1.0
0.8
© Schlumberger
268
pc =
1.2
Charts Perm-1 and Perm-2 can be used to recognize zones at irreducible water saturation, for which the product ϕSwi from levels within
the zone is generally constant and plots parallel to the ϕSwi lines.
Perm
2.3
Chart Perm-1: ϕS´wi = 0.072% and k = 130 mD.
Chart Perm-2: ϕS´wi = 0.072% and k = 65 mD.
(3)
The charts are valid only for zones at irreducible water saturation.
Enter porosity (ϕ) and Swi on a chart. Their intersection defines
the intrinsic (absolute) rock permeability (k). Medium-gravity oil is
assumed. If the saturating hydrocarbon is other than medium-gravity
oil, a correction factor (C′) based on the fluid densities of water and
hydrocarbons (ρw and ρh, respectively) and elevation above the freewater level (h) should be applied to the Swi value before it is entered
on the chart. The chart on this page provides the correction factor
based on the capillary pressure:
pc =
2.3
) = 120(1.1 − 0.3) = 42.
Enter the correction factor chart with Swi = 30% to intersect the curve for pc = 40 (nearest to 42), for which the
correction factor is 1.08. The corrected Swi value is S´wi =
1.08 × 30% = 32.4%.
Chart Perm-2 presents the results of another study:
 1 − S wi 
k 1/ 2 = 70φ2e 
.
 S wi 
(
h ρ w − ρh
(1)
Chart Perm-1 presents the results of one study for which the
observed relation was
 100φ 2.25 
k 1/ 2 = 
.
 S wi 
ϕ = 23 p.u., Swi = 30%, gas saturation with ρh = 0.3 g/cm3
and ρw = 1.1 g/cm3, and h = 120 ft.
Correction factor and k.
First, find pc to determine the correction factor if the
zone of interest is not at irreducible water saturation:
0
20
40
60
80
Irreducible water saturation, Swi (%)
100
Permeability
General
Permeability from Porosity and Water Saturation
Perm-1
Open Hole
(former K-3)
60
0.5
0.2
50
0.01
1.0
0.1
2
40
Irreducible
water
saturation
above
transition
zone,
Swi (%)
φSwi
5
0.12
10
20
30
0.10
Pe
rm
ea
bil
ity
,
50
k(
mD
)
100
200
20
0.04
0.08
0.06
500
1,000
2,000
5,000
0.02
10
0.01
0
0
5
10
15
20
25
30
35
40
Porosity, φ (p.u.)
© Schlumberger
Perm
269
General
Permeability
Permeability from Porosity and Water Saturation
Perm-2
Open Hole
(former K-4)
40
35
5,000
30
2,000
Porosity,
φ (p.u.)
1,000
500
20
200
)
mD
,k(
lity
abi
me
Per
25
φSwi
0.12
0.10
100
15
0.08
50
20
10
10
0.06
0.04
5
1
0.02
0
0.10
0.01
5
0.01
0
10
20
30
40
50
60
70
Irreducible water saturation above transition zone, Swi (%)
© Schlumberger
This chart is used similarly to Chart Perm-1 for the relation
 1 − S wi 
k 1/ 2 = 70φ2e 
.
 S wi 
Perm
270
80
90
100
Permeability
General
Fluid Mobility Effect on Stoneley Slowness
Perm-3
Open Hole
Fresh Mud at 600 Hz
10,000
Membrane impedance
1,000
Mobility
(mD/cp)
10
50
1
5
0 GPa/cm
(no mudcake)
100
10
0.1
0.1
1
10
100
Mobility-added slowness, S – Se (µs/ft)
© Schlumberger
Purpose
This chart is used to estimate ease of movement through a formation
by a fluid.
Description
The mobility-added slowness, which is the difference between the
Stoneley slowness and the calculated elastic Stoneley slowness, is
plotted on the x-axis and the mobility of the fluid is on the y-axis. The
membrane impedance curves represent the effect that the mudcake
has on the determination of the mobility of the fluid in the formation.
The membrane impedance is scaled in gigapascal per centimeter.
Perm
271
Cement
General Evaluation—Wireline
Cement Bond Log—Casing Strength
Interpretation—Cased Hole
Purpose
This chart is used to determine the decibel attenuation of casing
from the measured cement bond log (CBL) amplitude and convert
it to the compressive strength of bonded cement (either standard
or foamed).
Description
The amplitude of the first casing arrival is recorded by an acoustic
signal-measuring device such as a sonic or cement bond tool. This
amplitude value is a measure of decibel attenuation that can be
translated into a bond index (an indication of the percent of casing
cement bonding) and the compressive strength (psi) of the cement
at the time of logging.
Enter the chart on the y-axis with the log value of CBL amplitude
and move upward parallel to the 45° lines to intersect the appropriate
casing size. At that point, move horizontally right to the attenuation scale on the right-hand y-axis. From this point, draw a line
through the appropriate casing thickness value to intersect the compressive strength scale. The casing wall thickness is calculated by
subtracting the nominal inside diameter (ID) from the outside
diameter (OD) listed on the table for threaded nonupset casing
and dividing the difference by 2.
Cem
272
Example
Given:
Log amplitude reading = 3.5 mV in zone of interest
and 1.0 mV in a well-bonded section (usually the lowest
millivolt value on the log), casing size = 7 in. at
29 lbm/ft, casing thickness = 0.41 in., and neat cement
(not foamed).
Find:
Compressive strength and bond index of the cement at the
time of logging.
Answer:
Enter the 3.5-mV reading on the left y-axis of Chart
Cem-1 and proceed to the 7-in. casing line.
Move horizontally to intersect the right-hand y-axis at
8.9 dB/ft.
Determine the casing thickness as (7 – 6.184)/2 = 0.816/2
= 0.41 in. Draw a line from 8.9 dB/ft through the 0.41-in.
casing thickness point to the compressive strength scale.
Cement compressive strength = 2,100 psi.
To find the bond index, determine the decibel attenuation of the
lowest recorded log value by entering 1.0 mV on the left-hand y-axis
and proceeding to the 7-in. casing line. Move horizontally to intersect
the right-hand y-axis at 12.3 dB/ft.
Divide the precisely determined decibel attenuation for the CBL
amplitude in the zone of interest by this value for the lowest millivolt
value: 8.9/12.3 = 72% bond index.
A 72% bond index means that 72% of the casing is bonded. This
is not a well-bonded zone because a value of 80% bonding over a 10-ft
interval is historically considered well bonded. Although the logging
scale is a linear millivolts scale, the decibel attenuation scale is logarithmic. The millivolts log scale for the CBL value cannot rescaled
in percent of bonding. If it were, the apparent percent bonding
would be 65% because most bond log scales are from 0 to 100 mV
reading from left to right, over 10 divisions of track 1, or conversely
100% to 0% cement bonding for 0 mV = 100% bonding and
100 mV = 0% bonding.
Cement Evaluation—Wireline
Cement Bond Log—Casing Strength
Interpretation—Cased Hole
Threaded Nonupset Casing
OD
(in.)
Weight
per ft†
(lbm)
Nominal
ID
(in.)
Drift
Diameter‡
(in.)
4
11.60
3.428
3.303
41⁄2
9.50
11.60
13.50
4.090
4.000
3.920
3.965
3.875
3.795
43⁄4
16.00
4.082
3.957
5
11.50
13.00
15.00
17.70
18.00
21.00
4.560
4.494
4.408
4.300
4.276
4.154
4.435
4.369
4.283
4.175
4.151
4.029
51⁄2
13.00
14.00
15.00
15.50
17.00
20.00
23.00
5.044
5.012
4.974
4.950
4.892
4.778
4.670
4.919
4.887
4.849
4.825
4.767
4.653
4.545
53⁄4
14.00
17.00
19.50
22.50
5.290
5.190
5.090
4.990
5.165
5.065
4.965
4.865
6
15.00
16.00
18.00
20.00
23.00
5.524
5.500
5.424
5.352
5.240
5.399
5.375
5.299
5.227
5.115
65⁄8
17.00
20.00
22.00
24.00
26.00
26.80
28.00
29.00
32.00
6.135
6.049
5.989
5.921
5.855
5.837
5.791
5.761
5.675
6.010
5.924
5.864
5.796
5.730
5.712
5.666
5.636
5.550
OD
(in.)
Weight
per ft†
(lbm)
Nominal
ID
(in.)
Drift
Diameter‡
(in.)
7
17.00
20.00
22.00
23.00
24.00
26.00
28.00
29.00
30.00
32.00
35.00
38.00
40.00
6.538
6.456
6.398
6.366
6.336
6.276
6.214
6.184
6.154
6.094
6.004
5.920
5.836
6.413
6.331
6.273
6.241
6.211
6.151
6.089
6.059
6.029
5.969
5.879
5.795
5.711
75⁄8
20.00
24.00
26.40
29.70
33.70
39.00
7.125
7.025
6.969
6.875
6.765
6.625
7.000
6.900
6.844
6.750
6.640
6.500
85⁄8
24.00
28.00
32.00
36.00
38.00
40.00
43.00
44.00
49.00
8.097
8.017
7.921
7.825
7.775
7.725
7.651
7.625
7.511
7.972
7.892
7.796
7.700
7.650
7.600
7.526
7.500
7.386
9
34.00
38.00
40.00
45.00
55.00
8.290
8.196
8.150
8.032
7.812
8.165
8.071
8.025
7.907
7.687
95⁄8
29.30
32.30
36.00
40.00
43.50
47.00
53.50
9.063
9.001
8.921
8.835
8.755
8.681
8.535
8.907
8.845
8.765
8.679
8.599
8.525
8.379
OD
(in.)
Weight
per ft†
(lbm)
Nominal
ID
(in.)
Drift
Diameter‡
(in.)
10
33.00
9.384
9.228
103⁄4
32.75
40.00
40.50
45.00
45.50
48.00
51.00
54.00
55.50
10.192
10.054
10.050
9.960
9.950
9.902
9.850
9.784
9.760
10.036
9.898
9.894
9.804
9.794
9.746
9.694
9.628
9.604
113⁄4
38.00
42.00
47.00
54.00
60.00
11.150
11.084
11.000
10.880
10.772
10.994
10.928
10.844
10.724
10.616
12
40.00
11.384
11.228
13
40.00
12.438
12.282
133⁄8
48.00
12.715
12.559
16
55.00
15.375
15.187
185⁄8
78.00
17.855
17.667
20
90.00
19.190
19.002
211⁄2
92.50
103.00
114.00
20.710
20.610
20.510
20.522
20.422
20.322
241⁄2
100.50
113.00
23.750
23.650
23.562
23.462
† Weight per foot in pounds is given for plain pipe (no threads
or coupling).
‡ Drift diameter is the guaranteed minimum inside diameter of
any part of the casing. Use drift diameter to determine the
largest-diameter equipment that can be safely run inside the
casing. Use inside diameter for volume capacity calculations.
continued on next page
273
Cem
General Evaluation—Wireline
Cement
Cement Bond Log—Casing Strength
Cem-1
Interpretation—Cased Hole
(former M-1)
Casing size (mm)
194
140
176
115
Centered tool only, 3-ft [0.914-m] spacing
273
340
Attenuation
(dB/m)
1
70
4
2
50
CBL amplitude
(mV)
Compressive strength
(psi)
(mPa)
8
40
3
30
4
12
30
4,000
16
20
5
15
6 20
10
9
8
7
6
7
5
9
25
3,000
20
Casing thickness
(mm)
(in.)
0.6
15
24
0.5
8
28
4
10
32
0.4
10
10
8
0.3
7
3
6
2
12
13
1
0.5
5
16
13 3/8
3
10 /4
7
51/2
Foamed cement
500
250
3
52
(dB/ft)
500
4
48
100
300
200
1
100
3
2
1
0.5
2
50
75/8
Casing size (in.)
274
5
18
0.2
41/2
5
6
0.2
44
17 56
© Schlumberger
800
40
14
15
1,000
1,000
11 36
Cem
15
2,000
9 lbm
7 in. at 2
0.3
Standard
cement
Appendix A
Linear Grid
275
Appendix AA
Appendix
9
8
7
6
5
4
3
2
1
9
8
7
6
5
4
3
2
276
1
Log-Linear Grid
Water Saturation Grid for Resistivity Versus Porosity
Appendix AA
Appendix
For FR =
5,000
0.62
φ2.15
0.20
Resistivity scale may be
multiplied by 10 for use
in a higher range
4,000
0.25
0.30
3,000
2,500
0.35
0.40
0.45
2,000
0.50
0.60
1,500
0.70
0.80
Conductivity
(mmho/m)
1,000
0.90
1.0
Resistivity
(ohm-m)
1.2
500
1.4
1.6
1.8
2.0
400
2.5
300
200
150
100
50
25
10
0
3.0
4.0
5.0
6.0
8.0
10
15
20
30
40
50
100
200
∞
ρb
φ
FR
277
Water Saturation Grid for Resistivity Versus Porosity
Appendix AA
Appendix
For FR =
500
1
φ2
2
Resistivity scale may be
multiplied by 10 for use
in a higher range
400
2.5
3
300
3.5
250
4
4.5
200
5
6
150
Conductivity
(mmho/m)
7
8
100
9
10
12
14
16
50
20
40
25
30
30
40
20
50
10
100
5
200
500
1,000
2,000
0
∞
ρb
φ
FR
278
Resistivity
(ohm-m)
Logging Tool Response in Sedimentary Minerals
Appendix B
Name
Formula
ρlog
(g/cm3)
ϕSNP
(p.u.)
ϕCNL
(p.u.)
ϕAPS†
(p.u.)
Δt c
(μs/ft)
–1
56.0
Δt s
Pe
U
ε
(μs/ft) (farad/m)
tp
(ns/m)
Gamma Ray
(gAPI Units)
Σ
(c.u.)
Silicates
Quartz
SiO2
2.64
–1
–2
β-cristobalite
SiO2
2.15
–2
Opal (3.5% H2O)
SiO2 (H2O)0.1209
2.13
Garnet ‡
Fe3Al2(SiO4)3
1.8
4.8
–3
1.8
3.9
3.5
4
2 58
1.8
3.7
5.0
4.31
3
7 11
48
45
Hornblende ‡
Ca2NaMg2Fe2
AlSi8O22(O,OH)2
3.20
4
8 43.8
6.0
19
18
Tourmaline
NaMg3Al6B3Si6O2(OH)4
3.02
16
22
2.1
6.5
7450
Zircon
ZrSiO4
4.50
–1
–3
Calcite
CaCO3
2.71
0
0
0
49.0
88.4
5.1
13.8
7.5
9.1
7.1
Dolomite
CaCO3MgCO3
2.85
2
1
1
44.0
72
3.1
9.0
6.8
8.7
4.7
Ankerite
Ca(Mg,Fe)(CO3)2
2.86
0
1
Siderite
FeCO3
3.89
5
12
Hematite
Fe2O3
5.18
4
11 42.9
Magnetite
Fe3O4
5.08
3
Goethite
FeO(OH)
4.34
50+
60+
19
83
85
Limonite‡
FeO(OH)(H2O)2.05
3.59
50+
60+
13
47
71
Gibbsite
Al(OH)3
2.49
50+
60+
Hydroxyapatite
Ca5(PO4)3OH
3.17
5
8 42
5.8
18
Chlorapatite
Ca5(PO4)3Cl
3.18
–1
–1 42
6.1
19
Fluorapatite
Ca5(PO4)3F
3.21
–1
–2 42
5.8
19
8.5
Carbonapatite
(Ca5(PO4)3)2CO3H2O
3.13
5
8
5.6
17
9.1
Orthoclase
KAlSi3O8
2.52
–2
–3
69
2.9
7.2
4.4–6.0
7.0–8.2
~220
16
Anorthoclase
KAlSi3O8
2.59
–2
–2
2.9
7.4
4.4–6.0
7.0–8.2
~220
16
Microcline
KAlSi3O8
2.53
–2
–3
2.9
7.2
4.4–6.0
7.0–8.2
~220
16
1.7
4.4
4.4–6.0
7.0–8.2
7.5
45
3.1
8.6
4.4–6.0
7.0–8.2
7.2
49
2.4
6.7
6.2–7.9
8.3–9.4
88.0
81.5
69
311
4.65
7.2
4.3
6.9
Carbonates
3
47
9.3
15
27
22
57
52
6.8–7.5
8.8–9.1
Oxidates
79.3
9 73
56.9
102.6
21
111
101
22
113
103
9.9–10.9
10.5–11.0
1.1
23
Phosphates
9.6
130
Feldspars—Alkali‡
Feldspars—Plagioclase‡
Albite
NaAlSi3O8
2.59
–1
–2
–2
Anorthite
CaAl2Si2O8
2.74
–1
–2
KAl2(Si3AlO10)(OH)2
2.82
12
K0.7(Mg,Fe2,Al)
(Si4,Al10)O2(OH)
2.86 ~38
49
85
Micas‡
Muscovite
Glauconite
~21
149
~270
17
~15
4.8
14
21
~11
6.3
19
30
K(Mg,Fe)3(AlSi3O10)(OH)2
Phlogopite
KMg3(AlSi3O10)(OH)2 50
‡Mean
~11
~13
Biotite
†APS*
~2.99
~20
50.8
224
4.8–6.0
7.2–8.1
~275
207
33
Accelerator Porosity Sonde porosity derived from near-to-array ratio (APLC)
value, which may vary for individual samples
For more information, see Reference 41.
279
Logging Tool Response in Sedimentary Minerals
Appendix B
Name
Formula
ρlog
(g/cm3)
ϕSNP
(p.u.)
ϕCNL
(p.u.)
ϕAPS†
(p.u.)
Δt c
(μs/ft)
Δt s
Pe
U
(μs/ft)
ε
Gamma Ray
(gAPI Units)
Σ
(c.u.)
~8.0
80–130
14
~5.8
~8.0
180–250
25
(farad/m)
tp
(ns/m)
~5.8
Clays‡
Kaolinite
Al4Si4O10(OH)8
2.62
34
~37
~34
1.48
3.87
Chlorite
(Mg,Fe,Al)6(Si,Al)4
O10(OH)8
2.76
37
~52
~35
6.3
Illite
K1–1.5Al4(Si7–6.5,Al1–1.5)
O20(OH)4
2.77
20
~30
~17
2.33
6.45
~5.8
~8.0
250–300
18
Montmorillonite
(Ca,Na)7(Al,Mg,Fe)4
(Si,Al)8O20(OH)4(H2O)n
2.12~60
~60
2.0
4.0
~5.8
~8.0
150–200
14
Halite
NaCl
2.04
–2
–3
21
4.7
9.5
Anhydrite
CaSO4
2.98
–1
–2
2
Gypsum
CaSO4(H2O)2
2.35
50+
60+
60
Trona
Na2CO3NaHCO3H2O
2.08
24
Tachhydrite
CaCl2(MgCl2)2(H2O)12
1.66
Sylvite
KCl
Carnalite
Langbeinite
17
Evaporites
67.0
120
7.9–8.4
754
6.3
8.4
12
4.1
6.8
19
50
5.1
52
4.0
9.4
35 65
0.71
1.5
16
50+
60+ 92
3.8
6.4
406
1.86
–2
–3
8.5
KClMgCl2(H2O)6
1.57
41
60+
4.1
6.4
~220
369
K2SO4(MgSO4)2
2.82
–1
–2
3.6
10
~290
24
K2SO4Mg
SO4(CaSO4)2(H2O)2
2.79
14
25
4.3
12
~200
24
Kainite
MgSO4KCl(H2O)3
2.12
40
60+
3.5
7.4
~245
195
Kieserite
MgSO4(H2O)
2.59
38
43
1.8
4.7
14
Epsomite
MgSO4(H2O)7
1.71
50+
60+
1.2
2.0
21
Bischofite
MgCl2(H2O)6
1.54
50+
60+ 100
2.6
4.0
323
Barite
BaSO4
4.09
–1
–2
267
Celestite
SrSO4
3.79
–1
–1
55
209
Pyrite
FeS2
4.99
–2
–339.2
17
85
90
Marcasite
FeS2
4.87
–2
–3
17
83
88
Pyrrhotite
Fe7S8
4.53
–2
–3
21
93
94
Sphalerite
ZnS
3.85
–3
–3
36
138
Chalcopyrite
CuFeS2
4.07
–2
–3
27
109 102
Galena
PbS
6.39
–3
–3
Sulfur
S
2.02
–2
–3
Anthracite
CH0.358N0.009O0.022
1.47
37
38 105
0.16
0.23
Bituminous
CH0.793N0.015O0.078
1.24
50+
60+ 120
0.17
0.21
14
Lignite
CH0.849N0.015O0.211
1.19
47
52 160
0.20
0.24
13
Polyhalite
15
5.6–6.3
16
4.6–4.8
7.2–7.3
500+
1,090
565
6.8
7.9
Sulfides
62.1
122
1,630
5.4
7.8–8.1
9.3–9.5
25
10,400
13
11
20
Coals
†APS*
‡Mean
Accelerator Porosity Sonde porosity derived from near-to-array ratio (APLC)
value, which may vary for individual samples
For more information, see Reference 41.
280
8.7
Acoustic Characteristics of Common Formations and Fluids
Appendix C
Nonporous Solids
Δt
(µs/ft)
Material
Sound Velocity
(ft/s)
(m/s)
Acoustic Impedance
(MRayl)
Casing
57.0
17,500
5,334
41.60
Dolomite
43.5
23,000
7,010
20.19
Anhydrite
50.0
20,000
6,096
18.17
Limestone
47.6
21,000
6,400
17.34
Calcite
49.7
20,100
6,126
16.60
Quartz
52.9
18,900
5,760
15.21
Gypsum
52.6
19,000
5,791
13.61
Halite
66.6
15,000
4,572
9.33
Water-Saturated Porous Rock
Material
Porosity
(%)
Δt
(µs/ft)
Sound Velocity
(ft/s)
(m/s)
Acoustic Impedance
(MRayl)
Dolomite
5–20
50.0–66.6
20,000–15,000
6,096–4,572
16.95–11.52
Limestone
5–20
54.0–76.9
18,500–13,000
5,639–3,962
14.83–9.43
Sandstone
5–20
62.5–86.9
16,000–11,500
4,877–3,505
12.58–8.20
20–35
86.9–111.1
11,500–9,000
3,505–2,743
8.20–6.0
58.8–143.0
17,000–7,000
5,181–2,133
Sand
Shale
12.0–4.3
Liquids and Gases
Material
Δt
(µs/ft)
(ft/s)
(m/s)
Water
208
4,800
1,463
1.46
Water + 10% NaCl
192.3
5,200
1,585
1.66
Water + 20% NaCl
181.8
5,500
1,676
1.84
Seawater
199
5,020
1,531
1.57
Kerosene
230
4,340
1,324
1.07
Air at 15 psi, 32°F [0°C]
920
1,088
331
0.0004
Air at 3,000 psi, 212°F [100°C]
780
1,280
390
0.1
Sound Velocity
Acoustic Impedance
(MRayl)
281
Conversions
Appendix D
Length
Multiply
Number
of
➤
to
Obtain
Centimeters
Feet
Inches
Kilometers
Nautical
Miles
Meters
Mils
Miles
Millimeters
Yards
1
30.48
2.540
105
1.853 × 105
100
2.540 × 10–3
1.609 × 105
0.1
91.44
3.281 × 10–2
1
8.333 × 10–2
3281
6080.27
3.281
8.333 × 10–5
5280
3.281 × 10–3
3
0.3937
12
1
3.937 × 104
7.296 × 104
39.37
0.001
6.336 × 104
3.937 × 10–2
36
1
1.853
0.001
1.609
10–6
9.144 × 10–4
0.5396
1
5.396 × 10–4
0.8684
1853
1
1609
by
Centimeters
Feet
Inches
10–5
Kilometers
3.048 ×
10–4
2.540 ×
10–5
1.645 × 10–4
Nautical miles
Meters
0.01
0.3048
2.540 × 10–2
1000
Mils
393.7
1.2 × 104
1000
3.937 × 107
Miles
6.214 × 10–6
1.894 × 10–4
1.578 × 10–5
0.6214
10
304.8
25.40
105
1.094 × 10–2
0.3333
2.778 × 10–2
1094
Millimeters
Yards
3.937 × 104
1.1516
2027
2.540 ×
10–8
1
6.214 × 10–4
1
1000
2.540 × 10–2
1.094
2.778 × 10–5
1760
4.934 ×10–4
0.001
0.9144
39.37
3.6 × 104
6.214 × 10–7
5.682 × 10–4
1
914.4
1.094 × 10–3
1
Area
Multiply Acres
Number
of
➤
to
Obtain
Circular
Mils
Square
Square
Centimeters Feet
Square
Inches
Square
Kilometers
Square
Meters
Square
Miles
Square
Square
Millimeters Yards
by
Acres
2.296 × 10–5
1
247.1
2.471 × 10–4
2.066 × 10–4
640
Circular mils
1
1.973 × 105
1.833 × 108
1.273 × 106
Square
centimeters
5.067 × 10–6
1
929.0
6.452
1010
104
2.590 × 1010
0.01
8361
1.076 × 10–3
1
6.944 × 10–3
1.076 × 107
10.76
2.788 × 107
1.076 × 10–5
9
0.1550
144
1
1.550 × 109
1550
4.015 × 109
1.550 × 10–3
1296
4.047 × 10–3
10–10
9.290 × 10–8
6.452 × 10–10
1
10–6
2.590
10–12
8.361 × 10–7
4047
0.0001
9.290 × 10–2
6.452 × 10–4
106
1
2.590 × 106
10–6
0.8361
1.562 × 10–3
3.861 × 10–11
3.587 × 10–8
0.3861
3.861 × 10–7
1
3.861 × 10–13
3.228 × 10–7
100
9.290 × 104
645.2
1012
106
1
8.361 × 105
1.196 × 10–4
0.1111
7.716 × 10–4
1.196 × 106
1.196
1.196 × 10–6
1
Square feet
Square inches
Square
kilometers
Square meters
Square miles
4.356 × 104
6,272,640
Square
millimeters
Square yards
282
7.854 × 10–7
5.067 × 10–4
4840
1.973 ×109
1973
3.098 × 106
Conversions
Appendix D
Length
Multiply
Number
of
Bushels
(Dry)
Cubic
Centimeters
➤
Cubic
Feet
Cubic
Inches
Cubic
Meters
0.8036
4.651 × 10–4
28.38
Cubic
Yards
Gallons
(Liquid)
Liters
Pints
(Liquid)
Quarts
(Liquid)
by
2.838 × 10–2
Bushels (dry)
1
Cubic
centimeters
3.524 × 104
1
2.832 × 104
16.39
106
7.646 × 105
3785
1000
473.2
946.4
Cubic feet
1.2445
3.531 × 10–5
1
5.787 × 10–4
35.31
27
0.1337
3.531 × 10–2
1.671 × 10–2
3.342 × 10–2
Cubic inches
2150.4
6.102 × 10–2
1728
1
6.102 × 104
46,656
231
61.02
28.87
57.75
Cubic meters
3.524 × 10–2
10–6
2.832 × 10–2
1.639 × 10–5
1
0.7646
3.785 × 10–3
0.001
4.732 × 10–4
9.464 × 10–4
Cubic yards
1.308 × 10–6
3.704 × 10–2
2.143 × 10–5
1.308
1
4.951 × 10–3
1.308 × 10–3
6.189 × 10–4
1.238 × 10–3
Gallons (liquid)
2.642 × 10–4
7.481
4.329 × 10–3
264.2
202.0
1
0.2642
0.125
0.25
0.001
28.32
1.639 × 10–2
1000
764.6
3.785
1
0.4732
0.9464
Pints (liquid)
2.113 × 10–3
59.84
3.463 × 10–2
2113
1616
8
2.113
1
2
Quarts (liquid)
1.057 ×
29.92
1.732 ×
1057
807.9
4
1.057
0.5
1
Liters
35.24
10–3
10–2
Mass and Weight
Multiply
Number
of
Grams
Kilograms
Milligrams
Ounces†
Pounds†
Grains
1
15.43
1.543 × 104
1.543 × 10–2
437.5
7000
Grams
6.481 × 10–2
1
1000
0.001
28.35
Kilograms
6.481 × 10–5
0.001
1
10–6
Milligrams
64.81
1000
106
Ounces†
2.286 × 10–3
3.527 × 10–2
Pounds†
1.429 × 10–4
to
Obtain
➤
Grains
Tons
(Long)
Tons (Metric)
Tons (Short)
453.6
1.016 × 106
106
9.072 × 105
2.835 × 10–2
0.4536
1016
1000
907.2
1
2.835 × 104
4.536 × 105
1.016 × 109
109
9.072 × 108
35.27
3.527 × 10–5
1
16
3.584 × 104
3.527 × 104
3.2 × 104
2.205 × 10–3
2.205
2.205 × 10–6
6.250 × 10–2
1
2240
2205
2000­
9.842 × 10–7
9.842 × 10–4
9.842 × 10–10
2.790 × 10–5
4.464 × 10–4
1
0.9842
0.8929
10–6
0.001
10–9
2.835 × 10–5
4.536 × 10–4
1.016
1
0.9072
0.0005
1.120
1.102
1
by
Tons (long)
Tons (metric)
Tons (short)
† Avoirdupois
1.102 ×
10–6
1.102 ×
10–3
1.102 ×
10–9
3.125 ×
10–5
pounds and ounces
283
Conversions
Appendix D
Area
Multiply
Number
of
➤
to
Obtain
Atmospheres†
by
Bayres or Centimeters
Dynes per of Mercury
Square
at 0°C§
Centimeter‡
Inches of
Mercury at
0°C§
Inches of
Water at
4°C
Kilograms
per Square
Meter††
Pounds
per Square
Foot
Pounds
Tons
per Square (short)
Inch‡‡
per
Square
Foot
Pascals
1
9.869 × 10–7
1.316 × 10–2
3.342 × 10–2
2.458 × 10–3
9.678 × 10–5
4.725 × 10–4
6.804 × 10–2
0.9450
9.869 × 10–6
1.013 × 106
1
1.333 × 104
3.386 × 104
2.491 × 10–3
98.07
478.8
6.895 × 104
9.576 × 105
10
Centimeters
of mercury
at 0°C§
76.00
7.501 × 10–5
1
2.540
0.1868
7.356 × 10–3
3.591 × 10–2
5.171
71.83
7.501 × 10–4
Inches
of mercury
at 0°C§
29.92
2.953 × 10–5
0.3937
1
7.355 × 10–2
2.896 × 10–3
1.414 × 10–2
2.036
28.28
2.953 × 10–4
Inches of
water at 4°C
406.8
4.015 × 10–4
5.354
13.60
1
3.937 × 10–2
0.1922
27.68
384.5
4.015 × 10–3
Kilograms
per square
meter††
1.033 × 104
1.020 × 10–2
136.0
345.3
25.40
1
4.882
703.1
9765
0.1020
Pounds
per square
foot
2117
2.089 × 10–3
27.85
70.73
5.204
0.2048
1
144
2000
2.089 × 10–2
Pounds per
square inch‡‡
14.70
1.450 × 10–5
0.1934
0.4912
3.613 × 10–2
1.422 × 10–3
6.944 × 10–3
1
13.89
1.450 × 10–4
Tons (short) per
square foot
1.058
1.044 × 10–5
1.392 × 10–2
3.536 × 10–2
2.601 × 10–3
1.024 × 10–4
0.0005
0.072
1
1.044 × 10–5
1.013 × 105
10–1
1.333 × 103
3.386 × 103
2.491 × 10–4
9.807
47.88
6.895 × 103
9.576 × 104
1
Atmospheres†
Bayres or dynes
per square
centimeter‡
Pascals
†
One atmosphere (standard) = 76 cm of mercury at 0°C
‡
Bar
To convert height h of a column of mercury at t °C to the equivalent height h 0 at 0°C, use h 0 = h {1 – [(m – l ) t / 1 + mt]}, where m = 0.0001818 and l = 18.4 × 10–6 if the scale is
engraved on brass; l = 8.5 × 10–6 if on glass. This assumes the scale is correct at 0°C; for other cases (any liquid) see International Critical Tables, Vol. 1, 68.
†† 1 gram per square centimeter = 10 kilograms per square meter
‡‡ psi = MPa × 145.038
psi/ft = 0.433 × g/cm3 = lbf/ft3/144 = lbf/gal/19.27
§
Density or Mass per Unit Volume
Multiply
Number
of
➤
to
Obtain
Grams
per Cubic
Centimeter
Temperature
Kilograms
per Cubic
Meter
Pounds per
Cubic Foot
Pounds per
Cubic Inch
Pounds per
Gallon
by
Grams per cubic
centimeter
1
0.001
1.602 × 10–2
27.68
0.1198
Kilograms per
cubic meter
1000
1
16.02
2.768 × 104
119.8
Pounds per
cubic foot
62.43
6.243 × 10–2
1
1728
7.479
Pounds per
cubic inch
3.613 × 10–2
3.613 × 10–5
5.787 × 10–4
1
4.329 × 10–3
Pounds per
gallon
8.347
8.3 × 10–3
13.37 × 10–2
231.0
1
284
°F
1.8°C + 32
°C
5⁄9
°R
°F + 459.69
K
°C + 273.16
(°F – 32)
Symbols
Appendix E
Traditional
Symbol
Standard
SPE
and
SPWLA†
Standard
Description
Customary Unit or Relation
Computer
Symbol†
Standard
Reserve
Symbol‡
a
a
ACT
electrochemical activity
equivalents/liter, moles/liter
a
KR
COER
coefficient in FR – ϕ relation
FR = KR/ϕm
A
A
AWT
atomic weight
amu
C
C
ECN
conductivity (electrical logging)
millimho per meter (mmho/m)
σ
Cp
Bcp
CORCP
sonic compaction correction factor
ϕSVcor = BcpϕSV
Ccp
D
D
DPH
depth
ft, m
y, H
d
d
DIA
diameter
in.
D
E
E
EMF
electromotive force
mV
MR, a, C
V
/ϕm
F
FR
FACHR
formation resistivity factor
G
G
GMF
geometrical factor (multiplier)
fG
H
IH
HYX
hydrogen index
iH
h
h
THK
bed thickness, individual
d, e
I
I
–X
index
i
FFi
IFf
FFX
free fluid index
iFf
SI
Isl
SLX
silt index
Islt, isl, islt
Iϕ
PRX
porosity index
iϕ
Iϕ2
PRXSE
secondary porosity index
iϕ2
J
Gp
GMFP
pseudogeometrical factor
fGp
K
Kc
COEC
electrochemical SP coefficient
Ec = Kclog(aw/amf)
Mc, Kec
k
k
PRM
permeability, absolute (fluid flow)
mD
K
L
L
LTH
length, path length
ft, m, in.
s, l
M
M
SAD
slope, sonic interval transit time versus
density × 0.01, in M–N plot
M = [(τf – τLOG)/(ρb – ρf)] × 0.01
mθD
m
porosity (cementation) exponent
FR = KR/ϕm
N
N
SND
slope, neutron porosity versus
density, in M-N Plot
N = (ϕNf – ϕN)/(ρb – ρf)
n
n
SXP
saturation exponent
Swn = FRRw /Rt
P
C
CNC
salinity
g/g, ppm
SPI
p
Pc
m
p
Pc
MXP
PRS
PRSCP
Pe
†
‡
§
††
‡‡
pressure
capillary pressure
FR = KR
ft, m, in.
mϕND
c, n
2§
P
2§
Pc, pc
psi, kg/cm , atm
psi, kg/cm , atm
photoelectric cross section
SPE Letter and Computer Symbols Standard (1986).
Used only if conflict arises between standard symbols used in the same paper
The unit of kilograms per square centimeter to be replaced in use by the SI metric unit of the pascal
“DEL” in the operator field and “RAD” in the main-quantity field
Suggested computer symbol
285
Symbols
Appendix E
Traditional
Symbol
Standard
SPE
and
SPWLA†
Standard
Description
Customary Unit or Relation
Computer
Symbol†
Standard
Reserve
Symbol‡
Qv
shaliness (CEC per mL water)
meq/mL
FiMSHD
q
fϕshd
dispersed-shale volume fraction of
intermatrix porosity
ϕimfshd, q
R
R
RES
resistivity (electrical)
ohm-m
ρ, r
r
r
RAD
radial distance from hole axis
in.
R
S
S
SAT
saturation
fraction or percent
of pore volume
ρ, s
T
T
TEM
temperature
°F, °C, K
θ
BHT, Tbh
Tbh
TEMBH
bottomhole temperature
°F, °C, K
θBH
FT, Tfm
Tf
TEMF
formation temperature
°F, °C, K
t
t
TIM
time
μs, s, min
t
t
TAC
interval transit time
t
Δt
U
volumetric cross section
barns/cm3
v
v
VAC
velocity (acoustic)
ft/s, m/s
V, u
V
V
VOL
volume
cm3, ft3, etc.
v
V
V
VLF
volume fraction
Z
Z
ANM
atomic number
α
αSP
REDSP
SP reduction factor
γ
γ
SPG
specific gravity (ρ/ρw or ρg /ρair)
fv, Fv
s, Fs
ϕ
ϕ
POR
porosity
fraction or percentage
of bulk volume, p.u.
f, ε
ϕ1
PORPR
primary porosity
fraction or percentage
of bulk volume, p.u.
f1, e1
ϕ2
PORSE
secondary porosity
fraction or percentage
of bulk volume, p.u.
f2, e2
intergranular porosity
ϕig = (Vb – Vgr)/Vb
fig, εig
intermatrix porosity
ϕim = (Vb – Vma )/Vb
fim, εim
radial distance (increment)
in.
ΔR
sonic interval transit time
μs/ft
Δt
p.u.
ϕig
PORIG
ϕim
PORIM
Δr
Δr
DELRAD
Δt
t
TAC
ϕz, ϕim
††
ΔϕNex
DELPORNX
excavation effect
λ
Kani
COEANI
coefficient of anisotropy
ρ
ρ
‡‡
DEN
density
D
S
tdn
Σ
Σ
XST
XSTMAC
neutron capture cross section
macroscopic
c.u., cm–1
τ
TIMDN
thermal neutron decay time
μs
†
‡
§
††
‡‡
286
τdN
Mani
g/cm3
SPE Letter and Computer Symbols Standard (1986).
Used only if conflict arises between standard symbols used in the same paper
The unit of kilograms per square centimeter is to be replaced in use by the SI metric unit of the pascal.
“DEL” in the operator field and “RAD” in the main-quantity field
Suggested computer symbol
Subscripts
Appendix FE
Traditional
Subscript
Standard
SPE
and
SPWLA†
Standard
Explanation
Example
Computer
Subscript†
Standard
Reserve
Subscript‡
a
LOG
L
apparent from log reading
(or use tool description subscript)
RLOG, RLL
log
a
a
A
apparent (general)
Ra
ap
abs
cap
C
absorption, capture
Σcap
anh
anh
AH
anhydrite
b
b
B
bulk
ρb
B, t
bh
bh
BH
bottomhole
Tbh
w, BH
clay
cl
CL
clay
Vcl
cla
cor, c
cor
COR
corrected
tcor
c
c
C
electrochemical
Ec
cp
cp
CP
compaction
Bcp
D
D
D
density log
dis
shd
SHD
dispersed shale
Vshd
dol
dol
DL
dolomite
t dol
e, eq
eq
EV
equivalent
Rweq, Rmfeq
EV
f, fluid
f
F
fluid
ρf
fl
fm
f
F
formation (rock)
Tf
fm
g, gas
g
G
gas
Sg
G
gr
GR
grain
ρgr
gxo
gxo
GXO
gas in flushed zone
Sgxo
gyp
gyp
GY
gypsum
ρgyp
h
h
H
hole
dh
H
h
h
H
hydrocarbon
ρh
H
hr
hr
HR
residual hydrocarbon
S hr
i
i
I
invaded zone (inner boundary)
di
ig
ig
IG
intergranular (incl. disp. and str. shale)
ϕig
im, z
im
IM
intermatrix (incl. disp. shale)
ϕim
int
int
I
intrinsic (as opposed to log value)
Σint
irr
i
IR
irreducible
Swi
ir, i
J
j
J
liquid junction
Ej
ι
k
k
K
electrokinetic
Ek
ek
log
t pl
log
L
l L
lam
l
LAM
lamination, laminated
Vsh l
lim
lim
LM
limiting value
ϕlim
liq
L
L
liquid
ρL
†
‡
ec
d
GXO
I
l
SPE Letter and Computer Symbols Standard (1986).
Used only if conflict arises between standard symbols used in the same paper
287
Subscripts
Appendix FE
Traditional
Subscript
Standard
SPE
and
SPWLA†
Standard
Explanation
Example
Computer
Subscript†
Standard
Reserve
Subscript‡
log
LOG
L
log values
t LOG
log
ls
ls
LS
limestone
t ls
lst
m
m
M
mud
Rm
max
max
MX
maximum
ϕmax
ma
ma
MA
matrix
t ma
mc
mc
MC
mudcake
Rmc
mf
mf
MF
mud filtrate
Rm f
mfa
mfa
MFA
mud filtrate, apparent
Rmfa
min
min
MN
minimum value
ninoninvaded zone
Rni
o
o
O
oil (except with resistivity)
So
or
or
OR
residual oil
Sor
o, 0 (zero)
0 (zero)
ZR
100-percent water saturated
F0
N
zr
ppropagation
tpw
PSP
pSP
PSP
pseudostatic SP
EpSP
pri
1 (one)
PR
primary
ϕ1
p, pri
r
r
R
relative
k r o, k rw
R
r
r
R
residual
Sor , Shr
R
s
s
S
adjacent (surrounding) formation
Rs
sd
sd
SD
sand
sa
ss
ss
SS
sandstone
sst
sec
2
SE
secondary
ϕ2
s, sec
sh
sh
SH
shale
Vsh
sha
silt
sl
SL
silt
I sl
slt
SP
SP
SP
spontaneous potential
ESP
sp
SSP
SSP
SSP
static spontaneous potential
ESSP
str
sh st
SH ST
structural shale
Vshst
s
t, ni
t
T
true (as opposed to apparent)
Rt
tr
T
t
T
total
Ct
T
w
w
W
water, formation water
Sw
W
wa
wa
WA
formation water, apparent
Rwa
Wap
wf
wf
WF
well flowing conditions
pwf
f
ws
ws
WS
well static conditions
pws
s
xo
xo
XO
flushed zone
Rxo
z, im
im
IM
intermatrix
ϕim
†
‡
288
SPE Letter and Computer Symbols Standard (1986).
Used only if conflict arises between standard symbols used in the same paper
Subscripts
Appendix FE
Traditional
Subscript
Standard
SPE
and
SPWLA†
Standard
Explanation
Example
Computer
Subscript†
Standard
Reserve
Subscript‡
0 (zero)
0 (zero)
ZR
100 percent water saturated
R0
zr
AD
RAD
from CDR attenuation deep
RAD
D
D
D
from density log
ϕD
d
GG
GG
from gamma-gamma log
ϕGG
gg
IL
I
I
from induction log
RI
i
ILD
ID
ID
from deep induction log
RID
id
ILM
IM
IM
from medium induction log
RIM
im
LL
LL (also LL3,
LL
LL8, etc.)
from laterolog
(also LL3, LL7, LL8, LLD, LLS)
RLL
ll
N
N
N
from normal resistivity log
RN
n
N
N
N
from neutron log
ϕN
n
RPS
from CDR phase-shift shallow
RPS
16”, 16”N
from 16-in. normal Log
R16”
1” × 1”
from 1-in. by 1-in. microinverse (MI)
R1” × 1”
2”
from 2-in. micronormal (MN)
R2”
PS
†
‡
SPE Letter and Computer Symbols Standard (1986).
Used only if conflict arises between standard symbols used in the same paper
289
Appendix G
F
Unit Abbreviations
These unit abbreviations, which are based on those adopted by the
Society of Petroleum Engineers (SPE), are appropriate for most publications. However, an accepted industry standard may be used instead.
For instance, in the drilling field, ppg may be more common than
lbm/gal when referring to pounds per gallon.
In some instances, two abbreviations are given: customary and
metric. When using the International System of Units (SI), or metric,
abbreviations, use the one designated for metric (e.g., m3/h instead of
m3/hr). The use of SI prefix symbols and prefix names with customary
unit abbreviations and names, although common, is not preferred
(e.g., 1,000 lbf instead of klbf).
Unit abbreviations are followed by a period only when the abbreviation forms a word (for example, in. for inch).
curie . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ci
acre . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Spell out
dots per inch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . dpi
acre-foot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . acre-ft
electromotive force. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . emf
ampere . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A
electron volt. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . eV
ampere-hour . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-hr
farad . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F
angstrom unit (10–8 cm). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A
feet per minute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ft/min
atmosphere . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . atm
feet per second. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ft/s
atomic mass unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . amu
foot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ft
barrel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . bbl
foot-pound . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ft-lbf
barrels of fluid per day . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . BFPD
gallon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . gal
barrels of liquid per day . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . BLPD
gallons per day . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . gal/D
barrels of oil per day. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . BOPD
gallons per minute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . gal/min
barrels of water per day. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . BWPD
gigabyte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Gbyte
barrels per day . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B/D
gigahertz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GHz
barrels per minute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . bbl/min
gigapascal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GPa
billion cubic feet (billion = 109) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bcf
gigawatt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GW
billion cubic feet per day . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bcf/D
gram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . g
billion standard cubic feet per day . . . . . . . . . . . Use Bcf/D instead of Bscf/D
(see “standard cubic foot”)
hertz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hz
bits per inch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . bpi
horsepower-hour . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . hp-hr
bits per second . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . bps
brake horsepower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . bhp
British thermal unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Btu
capture unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . c.u.
centimeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . cm
centipoise. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . cp
centistoke . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . cSt
coulomb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C
counts per second . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . cps
cubic centimeter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . cm3
cubic foot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ft3
cubic feet per barrel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ft3/bbl
cubic feet per day . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ft3/D
cubic feet per minute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ft3/min
cubic feet per pound . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ft3/lbm
cubic feet per second . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ft3/s
cubic inch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . in.3
cubic meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . m3
cubic millimeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mm3
cubic yard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . yd3
290
dalton. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Da
darcy, darcies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D
day (customary) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D
day (metric). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . d
dead-weight ton. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . DWT
decibel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . dB
degree (American Petroleum Institute). . . . . . . . . . . . . . . . . . . . . . . . . . . °API
degree Celsius . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . °C
degree Fahrenheit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . °F
degree Kelvin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . See “kelvin”
degree Rankine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . °R
horsepower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . hp
hour (customary). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . hr
hour (metric). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . h
hydraulic horsepower. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . hhp
inch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . in.
inches per second . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . in./s
joule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . J
kelvin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . K
kilobyte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . kB
kilogram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . kg
kilogram-meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . kg-m
kilohertz. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . kHz
kilojoule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . kJ
kilometer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . km
kilopascal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . kPa
kilopound (force) (1,000 lbf) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . klbf
kilovolt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . kV
kilowatt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . kW
kilowatt-hour . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . kW-hr
kips per square inch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ksi
Unit Abbreviations
Appendix G
lines per inch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . lpi
pounds of proppant added . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ppa
lines per minute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . lpm
pounds per square inch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . psi
lines per second . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . lps
pounds per square inch absolute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . psia
liter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . L
pounds per square inch gauge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . psig
megabyte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MB
pounds per thousand barrels (salt content). . . . . . . . . . . . . . . . . . . . . . . . . ptb
megagram (metric ton) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mg
quart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . qt
megahertz. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MHz
reservoir barrel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . res bbl
megajoule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MJ
reservoir barrel per day . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RB/D
meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . m
revolutions per minute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . rpm
metric ton (tonne) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . t or Mg
saturation unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . s.u.
mho per meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ω/m
second . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . s
microsecond. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . µs
shots per foot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . spf
mile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Spell out
specific gravity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . sg
Ω
miles per hour . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mph
square . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . sq
milliamperes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mA
square centimeter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . cm2
millicurie . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mCi
square foot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ft2
millidarcy, millidarcies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mD
square inch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . in.2
milliequivalent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . meq
square meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . m2
milligram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mg
square mile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . sq mile
milliliter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mL
square millimeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mm2
millimeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mm
standard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . std
millimho . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mmho
standard cubic feet per day. . . . . . . . . . . . . . . . . . . . Use ft3/D instead of scf/D
(see “standard cubic foot”)
million cubic feet (million = 10 ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MMcf
6
milliPascal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mPa
standard cubic foot . . . . . . . . . . . . . . . . . Use ft3 or cf as specified on this list.
Do not use scf unless the standard
conditions at which the measurement
was made are specified.
The straight volumetric conversion factor
is 1 ft3 = 0.02831685 m3
millisecond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ms
stock-tank barrel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . STB
millisiemens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mS
stock-tank barrels per day. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . STB/D
millivolt. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mV
stoke . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . St
mils per year . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mil/yr
teragram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tg
minute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . min
thousand cubic feet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mcf
mole . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mol
thousand cubic feet per day. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mcf/D
nanosecond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ns
thousand pounds per square inch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . kpsi
newton . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N
thousand standard cubic feet per day . . . . . . . . Use Mcf/D instead of Mscf/D
(see “standard cubic foot”)
million cubic feet per day . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MMcf/D
million electron volts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MeV
million standard cubic feet per day . . . . . . . Use MMcf/D instead of MMscf/D
(see “standard cubic foot”)
ohm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ohm
ohm-centimeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ohm-cm
ohm-meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ohm-m
ounce. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . oz
parts per million . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ppm
pascal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pa
picofarad . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pF
pint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pt
porosity unit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . p.u.
pound (force) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . lbf
pound (mass) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . lbm
pound per cubic foot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . lbm/ft3
tonne (metric ton). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . t
trillion cubic feet (trillion = 1012) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tcf
trillion cubic feet per day . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tcf/D
volt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V
volume percent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vol%
volume per volume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vol/vol
watt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . W
weight percent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . wt%
yard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . yd
year (customary) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . yr
year (metric) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . a
pound per gallon. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . lbm/gal
291
Appendix H
G
1. Overton HL and Lipson LB: “A Correlation of the Electrical
Properties of Drilling Fluids with Solids Content,” Transactions,
AIME (1958)
2. Desai KP and Moore EJ: “Equivalent NaCl Concentrations from
Ionic Concentrations,” The Log Analyst (May–June 1969).
3. Gondouin M, Tixier MP, and Simard GL: “An Experimental Study
on the Influence of the Chemical Composition of Electrolytes on
the SP Curve,” JPT (February 1957).
4. Segesman FF: “New SP Correction Charts,” Geophysics
(December 1962)
No. 6, PI.
5. Alger RP, Locke S, Nagel WA, and Sherman H: “The Dual Spacing
Neutron Log–CNL,” paper SPE 3565, presented at the 46th SPE
Annual Meeting, New Orleans, Louisiana, USA (1971).
6. Segesman FF and Liu OYH: “The Excavation Effect,”
Transactions of the SPWLA 12th Annual Logging Symposium
(1971).
7. Burke JA, Campbell RL Jr, and Schmidt AW: “The Litho-Porosity
Crossplot,” Transactions of the SPWLA 10th Annual Logging
Symposium (1969), paper Y.
8. Clavier C and Rust DH: “MID-PLOT: A New Lithology
Technique,” The Log Analyst (November–December 1976).
9. Tixier MP, Alger RP, Biggs WP, and Carpenter BN: “Dual
Induction-Laterolog: A New Tool for Resistivity Analysis,” paper
713, presented at the 38th SPE Annual Meeting, New Orleans,
Louisiana, USA (1963).
10. Wahl JS, Nelligan WB, Frentrop AH, Johnstone CW, and
Schwartz RJ: “The Thermal Neutron Decay Time Log,” SPEJ
(December 1970).
11. Clavier C, Hoyle WR, and Meunier D: “Quantitative
Interpretation of Thermal Neutron Decay Time Logs, Part I and
II,” JPT (June 1971).
12. Poupon A, Loy ME, and Tixier MP: “A Contribution to Electrical
Log Interpretation in Shaly Sands,” JPT (June 1954).
13. Tixier MP, Alger RP, and Tanguy DR: “New Developments in
Induction and Sonic Logging,” paper 1300G, presented at the
34th SPE Annual Meeting, Dallas, Texas, USA (1959).
14. Rodermund CG, Alger RP, and Tittman J: “Logging Empty
Holes,” OGJ (June 1961).
15. Tixier MP: “Evaluation of Permeability from Electric Log
Resistivity Gradients,” OGJ (June 1949).
16. Morris RL and Biggs WP: “Using Log-Derived Values of Water
Saturation and Porosity,” Transactions of the SPWLA 8th
Annual Logging Symposium (1967).
17. Timur A: “An Investigation of Permeability, Porosity, and
Residual Water Saturation Relationships for Sandstone
Reservoirs,” The Log Analyst (July–August 1968).
292
References
18. Wyllie MRJ, Gregory AR, and Gardner GHF: “Elastic Wave
Velocities in Heterogeneous and Porous Media,” Geophysics
No. 1.
(January 1956)
19. Tixier MP, Alger RP, and Doh CA: “Sonic Logging,” JPT (May
1959)
No. 5.
20. Raymer LL, Hunt ER, and Gardner JS: “An Improved Sonic
Transit Time-to-Porosity Transform,” Transactions of the
SPWLA 21st Annual Logging Symposium (1980).
21. Coates GR and Dumanoir JR: “A New Approach to Improved
Log-Derived Permeability,” The Log Analyst (January–February
1974).
22. Raymer LL: “Elevation and Hydrocarbon Density Correction for
Log-Derived Permeability Relationships,” The Log Analyst
(May–June 1981).
23. Westaway P, Hertzog R, and Plasic RE: “The Gamma
Spectrometer Tool, Inelastic and Capture Gamma Ray
Spectroscopy for Reservoir Analysis,” paper SPE 9461,
presented at the 55th SPE Annual Technical Conference
and Exhibition, Dallas, Texas, USA (1980).
24. Quirein JA, Gardner JS, and Watson JT: “Combined Natural
Gamma Ray Spectral/Litho-Density Measurements Applied to
Complex Lithologies,” paper SPE 11143, presented at the 57th
SPE Annual Technical Conference and Exhibition, New Orleans,
Louisiana, USA (1982).
25. Harton RP, Hazen GA, Rau RN, and Best DL: “Electromagnetic
Propagation Logging: Advances in Technique and
Interpretation,” paper SPE 9267, presented at the 55th SPE
Annual Technical Conference and Exhibition, Dallas, Texas,
USA (1980).
26. Serra O, Baldwin JL, and Quirein JA: “Theory and Practical
Application of Natural Gamma Ray Spectrometry,” Transactions
of the SPWLA 21st Annual Logging Symposium (1980).
27. Gardner JS and Dumanoir JL: “Litho-Density Log
Interpretation,” Transactions of the SPWLA 21st Annual
Logging Symposium (1980).
28. Edmondson H and Raymer LL: “Radioactivity Logging
Parameters for Common Minerals,” Transactions of the SPWLA
20th Annual Logging Symposium (1979).
29. Barber TD: “Real-Time Environmental Corrections for the
Phasor Dual Induction Tool,” Transactions of the SPWLA 26th
Annual Logging Symposium (1985).
30. Roscoe BA and Grau J: “Response of the Carbon-Oxygen
Measurement for an Inelastic Gamma Ray Spectroscopy Tool,”
paper SPE 14460, presented at the 60th SPE Annual Technical
Conference and Exhibition, Las Vegas, Nevada, USA (1985).
Appendix H
31. Freedman R and Grove G: “Interpretation of EPT-G Logs in the
Presence of Mudcakes,” paper presented at the 63rd SPE
Annual Technical Conference and Exhibition, Houston, Texas,
USA (1988).
32. Gilchrist WA Jr, Galford JE, Flaum C, Soran PD, and Gardner JS:
“Improved Environmental Corrections for Compensated
Neutron Logs,” paper SPE 15540, presented at the 61st SPE
Annual Technical Conference and Exhibition, New Orleans,
Louisiana, USA (1986).
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