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International Workshop on CO２ Geological Storage , Japan ‘06

IWANOHARA

Time Lapse Well Logging

Geophysical Surveying CO.,LTD.

21 February 2006

Jiro Watanabe

Geophysical Surveying CO., LTD.

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International Workshop on CO２ Geological Storage , Japan ‘06Geophysical Surveying CO.,LTD.

Induction Log (Resistivity)

Neutron Log (Porosity)

Acoustic Log (Acoustic Velocity)

Observation wells with monitoring logs

Purpose of Time lapse well logging

2. Estimation of CO2 saturation.

1. Detection of carbon dioxide (CO2) breakthrough at

the observation wells.

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International Workshop on CO２ Geological Storage , Japan ‘06

Wireline logging unit at Iwanohara field

OB-2

OB-4OB-3

IW-1

Liquified CO2 Vessel

Logging Unit

Geophysical Surveying CO.,LTD.

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International Workshop on CO２ Geological Storage , Japan ‘06

3D configuration of the wells

CO2

Up Dip

Geophysical Surveying CO.,LTD.

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International Workshop on CO２ Geological Storage , Japan ‘06

Time lapse logging schedule

Geophysical Surveying CO.,LTD.

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International Workshop on CO２ Geological Storage , Japan ‘06

Results of time lapse logging (OB-2)

Geophysical Surveying CO.,LTD.

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International Workshop on CO２ Geological Storage , Japan ‘06

Mar. 10. 2004

CO2 Breakthrough (OB-2)

Geophysical Surveying CO.,LTD.

Feb. 12. 2004

Vp : 2.55 → 1.84 km/sec

0.71km/sec, 28% ▼

R : 5.02 → 5.56 Ω・m

0.54Ω・m, 11%△

φn : 0.24 → 0.14

0.10, 42%▼

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International Workshop on CO２ Geological Storage , Japan ‘06

Change of ΔVp (OB-2)

Acoustic Log

0.4

0.0 (km/sec)

-0.2

-0.4

Geophysical Surveying CO.,LTD.

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International Workshop on CO２ Geological Storage , Japan ‘06

Change of Δφn (OB-2)

Neutron Log

0.2

0.0 (frac)

-0.1

-0.2

Geophysical Surveying CO.,LTD.

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International Workshop on CO２ Geological Storage , Japan ‘06

Change of ΔR (OB-2)

Induction Medium Log

1.6

0.0 (Ω・m)

-0.8

0.8

Geophysical Surveying CO.,LTD.

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International Workshop on CO２ Geological Storage , Japan ‘06

Rate of changes (OB-2)

+0.4

0

-0.4

Vp

φn

R

CO2

Geophysical Surveying CO.,LTD.

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International Workshop on CO２ Geological Storage , Japan ‘06

Assumptions :

Estimation of CO2 saturation

◆ No gas and oil in the aquifer before CO2 breakthrough.

◆ The time lapse neutron log is equivalent the open hole

porosity log.

Geophysical Surveying CO.,LTD.

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International Workshop on CO２ Geological Storage , Japan ‘06Geophysical Surveying CO.,LTD.

Time lapse neutron log calibration

NMR log Vs Time lapse neutron log

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International Workshop on CO２ Geological Storage , Japan ‘06

Porosity Log (OB-2)

Geophysical Surveying CO.,LTD.

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International Workshop on CO２ Geological Storage , Japan ‘06

Change of Porosity (OB-2)

Geophysical Surveying CO.,LTD.

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International Workshop on CO２ Geological Storage , Japan ‘06

CO2 Saturation Map (OB-2)

Geophysical Surveying CO.,LTD.

0.0

0.6

0.3

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International Workshop on CO２ Geological Storage , Japan ‘06

Vp Response (OB-2, @1,116m)

Geophysical Surveying CO.,LTD.

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International Workshop on CO２ Geological Storage , Japan ‘06

Resistivity

Neutron

Geophysical Surveying CO.,LTD.

Conclusions 1

◆ The resistivity log is good in reproducibility.

◆ CO2 saturation from resistivity is smaller than CO2 saturation

from neutron log . It is difficult to estimate correct CO2 saturation from resistivity on present form. The phase behavior of CO2 inthe reservoir is still unknown.

◆ The hydrogen index measurement is easiest and certain way to

estimate CO2 saturation.

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International Workshop on CO２ Geological Storage , Japan ‘06Geophysical Surveying CO.,LTD.

◆ CO2 saturation can be presumed from change of Vp.

Conclusions 2

Acoustic

◆ The relation between Vp and CO2 saturation from neutron logagree with Gassmann theory.

◆ A small amount of CO2 causes a large drop in Vp.

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International Workshop on CO２ Geological Storage , Japan ‘06Geophysical Surveying CO.,LTD.

Jan. 13. 2006