Core-log integration

Alberto Malinverno

Well Logging Principles and ApplicationsG9947 - Seminar in Marine Geophysics

Spring 2008

Core-log integration issues

1. Measurement resolution

2. Depth matching

3. In situ versus laboratory conditions

Basalt

Sediment

After Goldberg, 1997

Core sample depth

Drilled interval

Recovered intervals

Shallowest possible depth

Deepest possible depth

Depth uncertainty

Missing interval

Core sample

20 300

50

100

150

200

250

300

Depth

(m

bsf)

Salinity300 400 500 600

Chlorinity (mM)0 0.2 0.4 0.6

0

50

100

150

200

250

300

GH saturation

Thin sands(1-3 cm)

9 cmsand

a b c

23 cmsand

Fig. 4 - Malinverno et al.

190

195

200

205

210

215

220

225

Depth

(m

bsf)

SFLU resistivity

(ohm m)

Hole U1325C

2 MHz 16in phase

resistivity (ohm m)

Hole U1325A

190

195

200

205

210

215

220

225

Ring resistivity

(ohm m)

Hole U1325A

9 cmsand

Depth

uncertainty

of sample

a b c

1 10 1 10 1 10

Fig. 5 - Malinverno et al.

0.2 0.4 0.6 0.8

50

100

150

200

250

Depth

(m

bsf)

Porosity1

Resistivity (ohm m)0 0.2 0.4 0.6

50

100

150

200

250

GH saturation

R0 R

t

Fig. 6 - Malinverno et al.

10

a b c

in si·tuin the natural or original position or placePronunciation: (")in-'sI-(")tü, -'si-, -(")tyü also -'sE-, -(")chüFunction: adverb or adjectiveEtymology: Latin, in positionDate: 1740

10

Random close packing of spheres:

density ≈ 0.64,porosity ≈ 0.36

Effective stress

• Stress or pressure: ρgh• Lithostatic stress at base column:

g(ρwhw + ρshs)• Hydrostatic pore pressure at

base column: gρw(hw + hs) • Effective stress (Terzaghi, 1936):

lithostatic stress – pore pressure

hwρw

hsρs

!e! = ghs("s ! "w)= ghs(1 ! #)("g ! "w)Base column

Wat

erSe

dim

ent

Multisensor track (MST)

Measurements on core samples

Measurements in the borehole

Sample

Sensors

“Sample”

Sensors

Wet bulk density measurement

137Ce source gamma-ray attenuation porosity evaluator (GRAPE)

P-wave velocity measurement

Transducer-receiver 500 kHz 2µsec pulse