Log Analysis
Using Microsoft Excel®
Focus on the Marcellus
Tim Carr
West Virginia University
My Observations
West Virginia University, November 17, 2010
Background
 Costs Are Becoming More Significant
High Land Costs
More Moderate Commodity Price
High Capital Costs
Horizontal Wells & Large Multi-Stage Fracture Stimulations
 Key Reservoir Parameters
Thickness
Unit Definitions (Formation  Bed)
Lithology
Thermal Maturity
Total Organic Carbon (TOC)
Gas Fraction (Adsorbed and Free)
Permeability
West Virginia University, November 17, 2010
AVERAGE WELL HEAD PRICE
 $2.95 per MMBtu 2002
 $6.25 per MMBtu 2007
 $7.96 per MMBtu 2008
 $3.71 per MMBtu 2009
 $4.33 per MMBtu 2010
$4.04 per MM Btu on 11/16/2010
EIA (http://www.eia.gov )
West Virginia University, November 17, 2010
Recent Growth in Natural Gas Production, Lower 48 States,
Attributed Largely to Unconventional Gas
65
Billion Cubic Feet per Day
9 % Growth Rate
60
55
50
45
0 % Growth Rate
Katrina & Rita
40
Date
(EIA, 2010)
West Virginia University, November 17, 2010
Natural Gas Supply by source,
1990-2030 (trillion cubic feet)
30
History
25
Projection
20
15
Unconventional
10
Net imports
Alaska
Non-associated offshore
5
Non-associated conventional
0
1990
1995
2000
2005
2010
Source: Energy Information Administration, Annual Energy Outlook 2009
2015
2020
2025
2030
West Virginia University, November 17, 2010
Marcellus Shale Resource
600
Marcellus
Resource
500
500
U.S. Resources
2,080 Tcf
100
220
Range Resources
200
256
Potential Gas Committee
300
Chesapeake Energy
Tcf
400
0
1 Potential
Gas Committee, June 18, 2009
U.S. Energy Information Administration
3 Marcellus Proved Reserves < 1 Tcf
2
1
U.S. Proved
Reserves
244 Tcf
2
Marcellus
Shale Resource
256 Tcf
3
Annual U.S.
Consumption
23 Tcf
West Virginia University, November 17, 2010
Marcellus Shale Production Forecasts
5.0
4.5
4.5
Wood Mackenzie
3.9
4.0
Penn State
3.5
2.9
Bcf/d
3.0
2.5
2.1
2.0
1.5
1.0
0.5
0.5
0.5
0.0
2010
2015
2020
Sources:
“An Emerging Giant: Prospects and Economic Impacts of Developing the Marcellus Shale Natural
Gas Play.” T. Considine, R. Watson, R. Entler, J. Sparks, The Pennsylvania State University, College of Earth &
Mineral Sciences, Department of Energy and Mineral Engineering. July 24, 2009.
Integrated Resource Plan for Connecticut. The Brattle Group. January 1, 2010. (Wood Mackenzie)
West Virginia University, November 17, 2010
Marcellus Shale Production Outlook
18
16
14
Bcf / d
12
10
8
6
4
2
Source: Williams Partners L.P.
2038
2036
2034
2032
2030
2028
2026
2024
2022
2020
2018
2016
2014
2012
2010
0
West Virginia University, November 17, 2010
Unconventional Resource Production
Technology, Economies of Scale, Integration
West Virginia University, November 17, 2010
Unconventional Resource Production
Technology, Economies of Scale, Integration
West Virginia University, November 17, 2010
Gas Shale Characteristics
 Very High Gamma Ray Activity (Kerogen Content)
High Uranium
 High Resistivity – Low Water Saturation
 Relatively Low Clay Content
Smectite to Illite Transition
 Low Bulk Density (Kerogen Content)
 Kerogen - Petrophysical Characteristics
Bulk Density
1.0 to 1.2 g/cm3
U
0.18 to 0.24
Neutron Porosity
50 to 65 p.u.
Gamma Ray Activity
500 to 4000 API
Sonic Slowness
160 µs/ft
West Virginia University, November 17, 2010
Three Approaches
 Logs to be used
Bulk Density
g/cm3
Density Porosity
Percent or Decimal
Neutron Porosity
Percent or Decimal
Photo-Electric
Barns
Gamma Ray
API Units
 Clay Typing – Related to Deposition & Diagensis
Spectral Gamma Ray Logs
Uranium (PPM), Thorium (PPM) and Potassium (Percent)
 Compositional Lithology Logs
Rhomaa-Umaa
Computational Analysis (Linear)
West Virginia University, November 17, 2010
Spreadsheets
 Ubiquitous and Low Cost
 Provide Some Hands-On Understanding of the Process
 Allow Easy Export to Higher End Packages
 Use Basic Logs
 Clay Typing
Estimate Uranium Content from Full Spectrum
Gamma-Ray Logs
 Compositional Lithology Logs
Rhomaa-Umaa
Computational Analysis (Linear)
 Organic Content (Next Time)
 Saturation (Next Time)
Heavily Modified Archie
West Virginia University, November 17, 2010
Gamma-Ray Log Analysis
U
Th
K
West Virginia University, November 17, 2010
Gamma-Ray Spectrum
Uranium
Thorium
West Virginia University, November 17, 2010
Gamma-Ray Spectrum
Schlumberger
Log Interpretation Principles
1989, Page 3-7
West Virginia University, November 17, 2010
Geochemists’ concept of typical
shale and black shale
North American Shale Composite
(NASC) Gromet et al. (1984)
Th 12.3 ppm, U 2.66 ppm, K 3.2%
GR = 121.7 API units
Black Shale Composite (BSC) Quinby-Hunt
et al. (1989)
Th 11.6 ppm, U 15.2 ppm, K 2.99%
GR = 215.8 API units
API unit multipliers: Th ppm 4 : U ppm 8 : K% 16
West Virginia University, November 17, 2010
Typical Spectral Gamma-Ray
Log Presentation Format
West Virginia University, November 17, 2010
Potassium-Thorium Crossplot
with
Generalized Mineral Fields (after Schlumberger)
West Virginia University, November 17, 2010
Potassium-Thorium Crossplot
with
Generalized Mineral Fields (after Schlumberger)
West Virginia University, November 17, 2010
Thorium and Uranium Concentration
and
Redox Potential
Adams and Weaver (1958)
West Virginia University, November 17, 2010
Gamma-Ray
and
Spectral Ratio Logs
Permian – Cretaceous
Central Kansas
West Virginia University, November 17, 2010
Photo-Electric and Spectral Gamma Ray
Schlumberger, Log Interpretation Principles 1989, Page 6-4
West Virginia University, November 17, 2010
Photo-Electric and Spectral Gamma Ray
Schlumberger, Log Interpretation Principles 1989, Page 6-4
West Virginia University, November 17, 2010
Idealized Kansas Pennsylvanian Cyclothem
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Spectral Gamma-Ray Log
Lansing Group, Wabaunsee County, Kansas
West Virginia University, November 17, 2010
Chestnut Drive Section
Spectral Gamma Ray Response
West Virginia University, November 17, 2010
Devonian Shale Analysis
Track 2
Track 1
Gamma Ray
200
Log
Depth(ft)
6685
0
API
Gamma Ray
API
400 0
Uranium
PPM
80
200 3
Bulk Density
G/CC
0
Log
Depth(ft)
6685
Harrell
Tully
HARRELL
6700
67 05
6700
6715
6720
6715
6730
6735
6730
TULLY
6745
6750
6745
6760
6765
6760
Mahantango
MAHANTANGO
6780
6775
6790
6795
6790
6775
6805
6810
6805
6820
68 2 5
6820
6835
6840
6835
6850
6855
6850
6865
6870
6865
6880
6885
6880
MARCELLUS
Marcellus
6895
6900
6895
6910
69 15
6910
6925
6930
6925
6940
6945
6940
Onondaga
ONONDAGA
6960
6955
6970
69 7 5
6970
HS=1
ONONDAGA_BASE
6985
6990
6985
PETRA 10/20/2009 12:03:52 AM (Type log Template.CSP)
6955
West Virginia University, November 17, 2010
Devonian Shale:
Oxidizing and Reducing Conditions
Oxidizing
• Reducing Vs.
Oxidizing
conditions
determined by
Th/U
West Virginia University, November 17, 2010
Devonian Shale: Clay Type
• Clay type can be
determined from
Th/K
•Illite-Pink
Smectite-Green
•Illite can increase
porosity by 4%
West Virginia University, November 17, 2010
Wells 1 & 3
West Virginia University, November 17, 2010
Wells 1 & 3
West Virginia University, November 17, 2010
Well 2
West Virginia University, November 17, 2010
Project 1
http://www.geo.wvu.edu/~tcarr/PTTC_11_2010
 Make sure you open an LAS File with Notepad
 Import a LAS File to EXCEL
Well 3.LAS
 Open Spectral Gamma Ray Template
Well 1.LAS
• Marcellus (7375’-7562’)
Well 2.LAS
• Marcellus (7359’-7501’)
 Create & Examine Plots
What is the difference in the two wells
West Virginia University, November 17, 2010
Open with Notepad
West Virginia University, November 17, 2010
Importing a LAS File to EXCEL
West Virginia University, November 17, 2010
Importing a LAS File to EXCEL
West Virginia University, November 17, 2010
Importing a LAS File to EXCEL
West Virginia University, November 17, 2010
West Virginia University, November 17, 2010
Introduction to Porosity Logs
 Porosity Logs DO NOT Directly Measure
Porosity
Acoustic (Sonic) Logs Measure Wave Travel
Time
Density Logs Measure Formation Bulk Density
Neutron Logs Measure Formation Hydrogen
Content
West Virginia University, November 17, 2010
Neutron Log Applications
 Porosity
 Lithology with Density and/or Sonic
 Gas Indicator
 Clay Content
 Correlation
 Cased Hole
West Virginia University, November 17, 2010
Neutron Tool Background
 Outgrowth of Work by Italian Physicists (1935)
 Slowing down and stopping of neutrons by a hydrogen rich material (e.g., water).
 Radioactive Source of High Energy Neutrons
 Americium and Beryllium
 Fairly Shallow Zone of Investigation
 ~ 6 inches (Flushed Zone (Rxo) in most cases)
 Neutrons lose energy each time they collide with nuclei as they travel through the
formation
 Greatest loss in energy when neutrons collide with nuclei of a similar mass
• Hydrogen atoms
 As the neutrons slow they can be captured and emit a gamma ray.
 Reduction in Neutron Flux (Increased Gamma Rays) is largely controlled by
concentration of hydrogen in the formation.
 Water (Oil) Filled Porosity in Flushed Zone of Clean Units
 Clays
 Lithology Effect
 Hydrocarbon Gas Effect
 Depress apparent neutron porosity
West Virginia University, November 17, 2010
The Neutron
Porosity Tool
West Virginia University, November 17, 2010
Historical Development of Neutron Logging
 Common Curve Mnemonics
 ΦN, PHIN, NPHI
 Usually Tracks 2 or 3 and dashed line.
 Units
 Counts
 %, Decimal Fraction
West Virginia University, November 17, 2010
Neutron Energy Loses
West Virginia University, November 17, 2010
Density Log Applications





Porosity
Lithology with PE, Neutron and/or Sonic
Gas Indicator
Synthetic Seismograms with Sonic
Rock Properties with Sonic
Poisson’s Ratio, Young’s Modulus
 Clay Content
 Borehole Conditions (Size and Rugosity)
West Virginia University, November 17, 2010
Density Tool Background
 Source of High Energy Gamma Rays
 Cesium 137
 Shallow Zone of Investigation
 <2 inches
 Gamma rays interact with the electron clouds of the atoms they encounter, with a
reduction in the gamma ray flux, which is measured by both a near and far detector.




Higher Energy Range Affected by Compton Scattering
Reduction is a function of the electron density of the formation
Number of Electrons Matched by the Number of Protons
In Most Cases Z/A = 0.5
• Z - Atomic Number
• A – Atomic Mass
 Two Density Values
 Bulk Density (RhoB or ρb) – Measured by Logging Tool – Solid + Fluid
• DEN, ZDEN
 Matrix Density (ρma) – Density of the Rock that has no Porosity
 Hydrocarbon Gas Effect
 Enhances apparent density porosity
West Virginia University, November 17, 2010
The
Formation
Density Tool
West Virginia University, November 17, 2010
Density Porosity
ΦD = (ρma – ρb) / (ρma – ρfluid)
DPHI, PHID, DPOR
Sandstone 2.644 gm/cm3
Limestone 2.710 gm/cm3
Dolomite 2.877 gm/cm3
Anhydrite 2.960 gm/cm3
Halite 2.040 gm/cm3
Freshwater 1.0 gm/cm3
Saltwater ~1.15 gm/cm3
West Virginia University, November 17, 2010
Question
Why does ΦN read
much higher
Than ΦD in the red boxed
area?
What are the general
lithologies
in this well?
West Virginia University, November 17, 2010
Photo Electric Pe Tool
 Lithology with Density, Neutron and/or Sonic
 Supplementary Measurement of the Density Tool
1970’s Onward
 Lower Energy Range Gamma Rays Affected by
Photoelectric Effect
Logged Value is a function of Z - Atomic Number
• Pe = (Z/10)3.6
• Barns per electron
 Only mild affect of Pore Volume and Fluid/Gas Content
Quartz = 1.81 Barns
Dolomite = 3.14 Barns
Calcite = 5.08 Barns
 Pe, PE, PEF
West Virginia University, November 17, 2010
Photoelectric factor log
qu artz dolomi te
cal cite
30% porosi ty
20%
10%
0
coal
k aoli n ite
i ll ite
s me cti te
5
ch lorite
an h ydrite
barn s /e l ectron
Pe
10
West Virginia University, November 17, 2010
Compositional Analysis
Combing More Than Two Logs
West Virginia University, November 17, 2010
Compositional Analysis
 Determine Lithology
Graphic Plots
Computation
 Identification and Semi-Quantitative Estimates
West Virginia University, November 17, 2010
Porosity Log Combinations
 Single Porosity Measurement
Lithology is Specified for Correct Porosity
• Choice of Matrix Value
 Two Porosity Measurements
Two Lithologies can be Predicted along with Porosity
 Three Porosity Measurements
Three Lithologies can be Predicted along with Porosity
 Greater the number of Measurements the Greater
the Complexity of the Lithology that can be
Estimated
West Virginia University, November 17, 2010
2 Logs
2 Minerals
West Virginia University, November 17, 2010
Dolomitic-Limestone System
West Virginia University, November 17, 2010
Three-Measurement Cross-Plot
 Three Mineral Matrix Can Be Determined
 Usually Reduce From 3-D to 2-D
Collapse the 3 measurements to two axes with
common denominator
 M-N Plots
Axis 1 – Sonic and Density
Axis 2 – Neutron and Density
Problem of Density and Sonic being Correlated
 Addition of Pe in Newer Methods
West Virginia University, November 17, 2010
M-N Cross Plot
West Virginia University, November 17, 2010
M – N Crossplot
 Remove the effect of pore fluid
Usually drilling fluid
 Combine Sonic and Density Logs (M)
M = (∆tfluid – ∆tmatrix) / (ρmatrix – ρfluid)
 Combine Neutron and Density
N = (Φnfluid – Φn matrix) / (ρmatrix – ρfluid)
West Virginia University, November 17, 2010
M-N Cross Plot
West Virginia University, November 17, 2010
RHOmaa – Umaa Crossplot
 Mineral Identification (MID) Plots
 Apparent Matrix Density RHOmaa
Density and Neutron
 Apparent Matrix Photoelectric Cross Section
Umaa
Density, Neutron and Photoelectric Effect
West Virginia University, November 17, 2010
Apparent Matrix Density
RHOmaa
West Virginia University, November 17, 2010
Photoelectric (PE) Factor
qu artz dolomi te
cal cite
30% porosi ty
20%
10%
0
coal
k aoli n ite
i ll ite
s me cti te
5
ch lorite
an h ydrite
barn s /e l ectron
Pe
10
West Virginia University, November 17, 2010
Volumetric Photoelectric Absorption
U/cm3
The photoelectric absorption
index (Pe) is measured in units
of barns per electron. In order to
linearize its relation with
composition, the variable must
be converted to a volumetric
photoelectric absorption index
(U) with units of barns per cc
and is approximated by:
West Virginia University, November 17, 2010
Volumetric Photoelectric Absorption
U of the matrix
This is the volumetric
photoelectric absorption
coefficient of the zone (matrix
plus fluid). The hypothetical
volumetric photoelectric
absorption coefficient of the
matrix is UMAA.
or approximated by
West Virginia University, November 17, 2010
Umaa Values (Apparent 𝜙)
West Virginia University, November 17, 2010
RHOmaa
Umaa
Plot
Pyrite
West Virginia University, November 17, 2010
Shale Characterization
West Virginia University, November 17, 2010
Computational Analysis
2 Logs
2 Minerals
West Virginia University, November 17, 2010
Computational Analysis
CV=L
V = C-1L
C - matrix of the log responses of the components
V - vector of the component proportions
L - vector of the log readings
To Solve for V need the inverse of the component
matrix
West Virginia University, November 17, 2010
Log response equations:
Rewritten as matrices:
West Virginia University, November 17, 2010
The compositional solution vector is
then given by pre-multiplying the log
response vector by the inverse of the
coefficient matrix
We are Saved - Easily computed in Excel
West Virginia University, November 17, 2010
West Virginia University, November 17, 2010
Compositional Analysis
West Virginia University, November 17, 2010
Project 2
http://www.geo.wvu.edu/~tcarr/PTTC_11_2010
 Use Parameters From Appendix B
 Open Compositional Template
Load in Separate Template Well 1.LAS
• Marcellus (7375’-7562’)
• Onondaga (7562.5’ 7578’)
• Why are data points outside the Rhomaa-Umaa Triangle
Load in Separate Template Well 2.LAS
• Marcellus (7359’-7501’)
• Onondaga (7501.5’ 7516’)
• Why are data points outside the Rhomaa-Umaa Triangle
 Create Computational Plots
What is the difference in the two wells West Virginia University, November 17, 2010
West Virginia University, November 17, 2010
My Observations
West Virginia University, November 17, 2010
West Virginia University, November 17, 2010
Tim Carr
Phone: 304.293.9660
Email: tim.carr@mail.wvu.edu
West Virginia University, November 17, 2010