Image Logging
Electrical
Borehole Wall Imaging
Formation Micro Imager
FMI
Oriented images of structures on the
borehole wall with resistivity contrasts.
4-Arm tool, each arm with pad &
foldable flap-pad, each pad with 24
electrode buttons (total 192).
4.08 -6.2 mm
Main pad
7.62 mm
5.08 mm
electrode
button
pattern
Flap pad
Vertical resolution:
5 mm
GFZ-OSG, J. Kück
FMS
FMI
Section: 628.7 - 630.4
Section: 957.5 - 959.0
FMS/FMI
in big
sized
holes
Example:
KTB main well,
bit size: 17 1/2"
GFZ-OSG, J. Kück
FMI in
big sized holes
Example: KTB main well,
bit size: 14 3/4"
Section: 4757.7 - 4760.3 m
GFZ-OSG, J. Kück
FMS - Vertical Fractures
GFZ-OSG, J. Kück
Fracture Detection using Images
Example:
EMI
Halliburton
GFZ-OSG, J. Kück
Fault Zone Detection using Images
Example:
EMI
Halliburton
GFZ-OSG, J. Kück
FMS Image
0
2533.3
60
KTB pilot hole, Gneiss foliation
120 180 240 300 360
2537.3
113/46
174/45
183/51
197/50
209/40
209/48
226/60
2534.0
2534.2
2538.3
GFZ-OSG, J. Kück
Image Logging
Acoustic
Borehole Wall Imaging
Borehole Televiewer - BHTV
BHTV sonde inside
borehole, rotating and
running upward
`Reading´ trace of the
sonic beam on the
borehole wall.
Sonic beam running
from transducer to the
wall and back
GFZ-OSG, J. Kück
BHTV
Exmpl: GeoSys
Acoustic Borehole Televiewer
Type: acoustic transducer rotating
inside housing
Logging speed: 1 - 10 m/min
Downhole electronics
Rotating coil to record
Azimuthal orientation in
earth magnetic field
Rotating transducer inside
oilfilled acoustic transparent
plastic housing
6 rps
Frequency: 800 kHz
GFZ-OSG, J. Kück
BHTV
Acoustic Borehole Televiewer
Type: acoustic
transducer
rotating in mud
Logging speed:
2 - 10 m/min
Motor & gear-box
assembly
Rotating electrical
connection
Centralizer
Rotating shaft with
built-in electronics
Rotating seal
Exmpl:
Schlumberger UBI
Transducer,
Frequency:
250/500 kHz
Interchangable
acoustic head
≈ 7.5 rps
GFZ-OSG, J. Kück
BHTV
Acoustic Image
0
60
120 180 240
KTB VB
300 360
FMS
Electric Image
0
2188.5
2188.5
2189.0
2189.0
2189.5
2189.5
2190.0
2190.0
2190.5
2190.5
2191.0
2191.0
60
120 180 240 300 360
GFZ-OSG, J. Kück
BHTV - Borehole Enlargement & Excentering
Color-Scale
1071.5
Grey-Scale
Example:
KTB VB
1072.5
1073.5
1073.38 m
1074.5
1075.5
Cross-Section
GFZ-OSG, J. Kück
N
1693.5 m
BHTV
W
S
Breakouts
1693.1
1693.5 m - 1694.0 m
Tensile
Fractures
SH
Breakouts in
minimal stress
ize
s
t
Bi
SH
1693.2
1693.3
direction of
Sh
1693.4
Stack of 5 depth slices
GFZ-OSG, J. Kück
E
1693.5
BHTV - Borehole Wall
Breakouts
3D-Projection:
1605.3 - 1605.8 m
Cross-Section:
1605.73 m
KTB VB
1602.8 - 1608.2 m
GFZ-OSG, J. Kück
Slip Failure in Borehole Cross-Sections
Shear Displacement
slip along strike of
pre-existing fault
dextral
normal motion
reverse motion
GFZ-OSG, J. Kück
slip along dip of
pre-existing fault
hole deviation
An
gle
btw
.
So
nd
ea
xis
&l
ay
er
Effect of
borehole deviation
on dip readings
apparent
dip angle
of
e
lec
t ro
de
s
GFZ-OSG, J. Kück
pla
ne
true dip angle,
horizontal
Geophysical Logging
Nuclear Logs
Neutron Porosity Sonde
Apparent Hydrogen Content
(increasing hydrogen = increasing gamma count)
Source: Neutrons
AmBe, 16 Curie, 4.5 MeV or accelerators
detectors
thermal,
3He
epithermal,
Lithium-Fluoride
≈ 25 cm
< 30 cm
Gamma generation
emitted 'capture
gamma'
incident
neutron
de-exciting nucleus emits gamma
! This log reacts sensitive on breakouts
=> high hydrogen readings. Also salt water
invasion will increase the hydrogen readings !
GFZ-OSG, J. Kück
source
Vertical resolution:
Depth of investigation:
Density Sonde - LDS
Rock Density (apparent)
(increasing density = decreasing electron count)
Source: Gamma Photons
! This log reacts sensitive on breakouts
=> low density readings !
long spacing
gamma
photon
energy
100-662 keV
short spacing
source
gamma
photon,
energy
<100 keV
scattered
photon
Compton
recoil electron
ejected
photoelectron
Photoeffect
GFZ-OSG, J. Kück
detectors:
scintillation
counters
Cs137, 1.5 Curie, 662 keV
Spectral Gamma Ray - SGR
Uranium, Thorium & Potassium Content
(radioactive decay series of
Source: Neutrons
238
U, 232Th & 40K)
AmBe, 16 Curie, 4.5 MeV or accelerators
dN
dE
40
Th + U + K
K
x10
scale
214
B
208
T
i
l
K
detector:
scintillation counter
with
energy windows
or
full spectrum
U
Th
Energy (MeV)
W1
W2
low energy
high count rate
W3
W4
W5
high energy
low count rate
GFZ-OSG, J. Kück
Elemental Analysis
(Geochemical Logging)
Example:
Schlumberger
GLT
Elements Concentration
(active and passive methods)
Natural
Gamma Ray
Spectrometry
thermal
Dual Energy
Neutron Tool
epithermal
Aluminum
Activation
Clay Tool
U, Th, K
Porosity
252Cf
Al
Mineral Composition
The GLT consists of three independent
spectrometry tools and a neutron tool.
Neutron Tool & Aluminum Activation Tool:
252Cf source, 2.35 MeV
Induced Gamma Ray Spectroscopy Tool:
pulsed neutron accelerator, 14 MeV
Induced
Gamma Ray
Spectroscopy
Tool
Si, Ca, Fe, S,
Gd, Ti, Cl, H
Boron sleeve
4.25"
Length: 21 m
The sonde is run eccentered.
Logging speed:
1-3 m/min
Vertical resolution:
Depth of investigation:
30-90 cm (1-3 ft)
<3m
GFZ-OSG, J. Kück
Geophysical Logging
Resistivity
Nuclear Magnetic Resonance - NMR
Free Hydrogen Content, Porosity, Permeability
(spin of hydrogen nuclei)
Example: CMR, Schlumberger
S
Magnet
N
14 ft
5.3 "
6"
Sensing region
≈ 0.5" x 0.5" x 6"
ca. 1.1 - 1.5" from skid
Antenna
S
Magnet
N
Blind Zone
≈ 0.5" x 0.5"
(1.3 x 1.3 cm)
5.3 "
Vertical resolution: 15 cm (6")
4.625
inch
GFZ-OSG, J. Kück
Resistivity - Dual Laterolog - DLL
Electrical Resistivity
(constant current focused into the rock, guard electrodes)
LLS
LLD
G
sensing current
focusing current
G
shallow:
> 250 Hz
deep:
35-150 Hz
Two depths of investigation
simultaneously :
deep, LLD:
150 - 220 cm
shallow, LLS: 60 - 90 cm
Vertical resolution: 60 cm
! The Laterolog is good both in
resistive and conductive formations.
!
It can not be used in bore holes filled
with non-conductive mud (oil & air). !
GFZ-OSG, J. Kück
Azimuthal Resistivity Imager - ARI
Electrical Resistivity Image
(like DLL, additionally in 30° segments)
LLD
LLS &
&
deep azimuthal
shallow
azimuthal
A2
G
A1
M2
M1
A0
M'1
M'2
A'1
G
A'2
Upper electrode A2 is
replaced by 12 single
electrodes, with monitor
electrode inside each.
The ARI image contains
absolut resistivity data.
! The azimuthal resolution
decreases rapidly with
increase of well diameter !
GFZ-OSG, J. Kück
Dual Induction Log - DIL
Electrical Resistivity
(induction of a ground loop current,
receiver current is proportional to rock conductivity)
Receiver coil
Emitter frequency:
20 kHz/40 kHz
Two depths of investigation
simultaneously:
medium ≈ 80 cm, deep ≈ 170 cm
Vertical resolution ≈ 1-2 m
Ground loop
Emitter coil
! The induction log should not be used in
resistive formations and in salt water wells.
It can be used in boreholes filled with
non-conductive mud (oil & air). !
GFZ-OSG, J. Kück
Micro Sperically Focused Log - MSFL
Electrical Resistivity, very shallow
(pad with electrode configuration, focused current, like laterolog)
Depth of investigation: 2 - 10 cm
Vertical resolution:
5 - 10 cm
caliper
arms
Electrode
pad
Ao
Mo
A1
Ao
measure
voltage
Mo
A1
∆V=0
monitor electrodes
GFZ-OSG, J. Kück
Density
Sonde
Breakouts
Sonde
with Pads
Rough
Wall
!Borehole
corrections have
to be applied !
! SGR/GR should
be run
excentered
Breakouts &
Wall Roughness
Borehole enlargements
affect mostly all standard
logs:
Density, Sonic, Porosity,
Resistivity, Gamma
A rough wall surface
causes blured readings in
sondes with very high
spatial resolution:
FMS/FMI etc., MSFL,
SHDT
GFZ-OSG, J. Kück
Geophysical Logging
Sonic Logs
Sonic Log
Speed of Sound
(recording of sound wave traveltimes)
upper
transmitter
receiver 1
Sonic frequency:
20 - 40 kHz
Depth of investigation: 100 cm
Vertical resolution:
60 cm
receiver 2
∆t2
∆t1
Full wave form recording
receiver 3
receiver 4
firing
Stonley wave
lower
transmitter
∆t = (∆t1+∆t2)/2
shear wave
compressional wave
GFZ-OSG, J. Kück
Array Sonic Tool
Different Sonic Sonde Designs
(multiple recording of sound wave traveltimes)
3.5 ft
8 receiver
array
8 ft
2 ft
2 receiver
3 ft
2 ft
2 transmitter
GFZ-OSG, J. Kück
Dipol Shear Sonic Imager - DSI
Different Sonic Sonde Designs
(generation of strong shear waves and multiple recording)
Compressional
Wave
Shear
Wave
Flexural
Wave
receiver
42 in array
6 in
Wellbore
Directional Source
Monopole
Compressional
Wave
Shear
Wave
3.5 ft
monopole
transmitter
9 ft
11 ft
11.5 ft
upper & lower
dipole transmitter
GFZ-OSG, J. Kück
Vertical Seismic Profiling - VSP
Seismic Signals
(depth profile of seismic velocities)
magnetic
anchoring
clamping arm
anchoring
Example: GFZ, BG-250
GFZ-OSG, J. Kück
Example: Schlumberger, ASI
Much larger integration volume
than with sonic logs
Geophysical Logging
Magnetic Logs
3D Magnetometer
Magnetic Field
(BVER, BHOR, BABS, Inclination)
The measured field consists of:
- the rock remanent field
- the induced rock field
- and the current earth‘s magnetic field
3 cartesian fluxgate magnetometers
3 accelerometers
mechanical or optical gyro-compass
Resolution ≈ 2.5 nT
Measuring range:
± 100 000 nT
GFZ-OSG, J. Kück
Sus Log
Magnetic Susceptibility
(emitter AC current induces a magnetic field to
rock, return field is according to susceptibility)
Frequency:
Measuring range:
units
Depth of investigation:
Vertical resolution:
Electronics
1 kHz
10-6-10-1 SI
≈ 20 cm
≈ 20 cm
Receiver Coil
Magnetic susceptibility of rocks
mainly depends on type, shape
and concentration of
ferromagnetic minerals (Fe-Ti).
Epoxy
housing
w/ oil filling
Compensator Coil
Emitter Coil
Example: MSdH, ANTARES
GFZ-OSG, J. Kück
Geophysical Logging
Gravimetry
Borehole Gravity Meter - BHGM
Gravity Profile & Density
(sensitive spring balance which measures changes
in weight of a proof mass due to changes in gravity)
Large integration volume: ø several 10 m
Maximum hole deviation ≈ 14°
! Allows density logging in cased holes
and in wells with extreme breakouts.
Gives density data in wells where
radioactive sources are prohibited !
Example: EDCON, BHGM sensor section
Stationary measurements ≈ 8 to 14 min each
GFZ-OSG, J. Kück
Geophysical Logging
Sidecores
Sidewall Coring Tool
Example: Halliburton
Coring in progress
anchoring arm
Collecting the core
core
pusher
hydraulic drill motor
drill bit
flexible hydraulic line
core storage tube
core
GFZ-OSG, J. Kück
core recovery indicator
Geophysical Logging
Conclusions
Depth of Investigation of Logging Sondes
Induction
Density
Laterolog
Neutron
Porosity
MSFL
micro resistivity
Gamma
Spectrum
Sonic
Imager
GFZ-OSG, J. Kück
Depth of Investigation & Vertical Resolution of Logging Sondes
100 in
250 cm
DPT
DIL, deep
Vertical Resolution, inch/cm
Phasor, deep
TDT
10
25
LLS
NGS
FDC
Phasor, medium
LLD
Sonic
CNT
GST
inelastic mode
SFL
LDT
Enhanced Phasor
GST
capture mode
GR
MSFL
EPT
Microlog
Microlaterolog
1
2.5
HDT
Dual
Dipmeter
0.2
0.5
Example: Schlumberger Sondes
FMS/FMI
0.4 in
1 cm
1
2.5
3
7.6
10
25
30
76
Depth of investigation, inch/cm
100
250
300
760
GFZ-OSG, J. Kück
A few questions about log data quality
• Is the recorded depth reliable and
how accurate is it?
• How did the borehole environment affect the
logging data? Mud? Caliper?
• Was the sonde centralized/excentralized?
• Was the logging sonde functioning normally?
See the remarks on the log or report!
• How reliable is the sonde response in the range
of interest?
• Has the processed data already been filtered?
GFZ-OSG, J. Kück