Core-log integration
Alberto Malinverno
Well Logging Principles and Applications
G9947 - Seminar in Marine Geophysics
Spring 2008
Core-log integration issues
1. Measurement resolution
2. Depth matching
3. In situ versus laboratory conditions
Sediment
Basalt
After Goldberg, 1997
Core sample depth
Shallowest
possible
depth
Core
sample
Drilled
interval
Recovered
intervals
Depth
uncertainty
Missing
interval
Deepest
possible
depth
Salinity
0
20
a
Depth (mbsf)
50
30
Chlorinity (mM)
300
b
400
500
600
GH saturation
0
0.2
0.4
0.6
0
c
Thin sands
(1-3 cm)
50
100
100
150
150
200
200
250
9 cm
sand
250
23 cm
sand
300
300
SFLU resistivity
(ohm m)
190
1
10
1
10
b
a
Depth (mbsf)
2 MHz 16in phase
resistivity (ohm m)
Ring resistivity
(ohm m)
1
10
190
c
195
195
200
200
205
9 cm
sand
Depth
uncertainty
of sample
205
210
210
215
215
220
220
225
225
Hole U1325C
Hole U1325A
Hole U1325A
Porosity
0.2
0.4
0.6
Resistivity (ohm m)
0.8
1
Depth (mbsf)
a
10
b
GH saturation
0
0.2
0.4
0.6
c
50
50
100
100
150
150
R0
Rt
200
200
250
250
in si·tu
in the natural or original position or place
Pronunciation: (")in-'sI-(")tü, -'si-, -(")tyü also
-'sE-, -(")chü
Function: adverb or adjective
Etymology: Latin, in position
Date: 1740
10
Random close
packing of
spheres:
density ≈ 0.64,
porosity ≈ 0.36
Water
Effective stress
ρw
hw
• Stress or pressure: ρgh
• Lithostatic stress at base column:
g(ρ h + ρ h )
• Hydrostatic pore pressure at
base column: gρ (h + h )
• Effective stress (Terzaghi, 1936):
w w
s s
Sediment
w
ρs
hs
Base column
w
s
lithostatic stress – pore pressure
σeff
=
=
gh s (ρ s − ρw )
gh s (1 − φ)(ρg − ρw )
Multisensor track (MST)
Measurements on
core samples
Measurements in
the borehole
Sensors
Sample
Sensors
“Sample”
Wet bulk density measurement
137Ce
source gamma-ray attenuation porosity evaluator (GRAPE)
P-wave velocity measurement
Transducer-receiver 500 kHz 2µsec pulse