IWANOHARA
Time Lapse Well Logging

Jiro Watanabe
Geophysical Surveying CO., LTD.

21 February 2006
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Geophysical Surveying CO.,LTD.

International Workshop on CO２ Geological Storage , Japan ‘06

Purpose of Time lapse well logging

1. Detection of carbon dioxide (CO2) breakthrough at
the observation wells.
2. Estimation of CO2 saturation.

Observation wells with monitoring logs
Induction Log (Resistivity)
Neutron Log (Porosity)
Acoustic Log (Acoustic Velocity)2
Geophysical Surveying CO.,LTD.

International Workshop on CO２ Geological Storage , Japan ‘06

Wireline logging unit at Iwanohara field

Liquified CO2 Vessel
OB-2OB-3
OB-4

IW-1Logging Unit
3Geophysical Surveying CO.,LTD.

International Workshop on CO２ Geological Storage , Japan ‘06

3D configuration of the wells

CO2Up Dip

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Geophysical Surveying CO.,LTD.

International Workshop on CO２ Geological Storage , Japan ‘06

Time lapse logging schedule

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Geophysical Surveying CO.,LTD.

International Workshop on CO２ Geological Storage , Japan ‘06

Results of time lapse logging (OB-2)

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Geophysical Surveying CO.,LTD.

International Workshop on CO２ Geological Storage , Japan ‘06

CO2 Breakthrough (OB-2)

Vp : 2.55 → 1.84 km/secφn : 0.24 → 0.14

R : 5.02 → 5.56 Ω・m

0.71km/sec, 28% ▼0.10, 42%▼0.54Ω・m, 11%△

Feb. 12. 2004

Mar. 10. 2004
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Geophysical Surveying CO.,LTD.

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

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Geophysical Surveying CO.,LTD.

International Workshop on CO２ Geological Storage , Japan ‘06

Change of Δφn (OB-2)
Neutron Log
0.2
0.0 (frac)

-0.1

-0.2

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Geophysical Surveying CO.,LTD.

International Workshop on CO２ Geological Storage , Japan ‘06

Change of ΔR (OB-2)
Induction Medium Log
1.60.80.0 (Ω・m)

-0.8

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Geophysical Surveying CO.,LTD.

International Workshop on CO２ Geological Storage , Japan ‘06

Rate of changes (OB-2)

Vp+0.4

φn0-0.4

R

CO211Geophysical Surveying CO.,LTD.

International Workshop on CO２ Geological Storage , Japan ‘06

Estimation of CO2 saturation
Assumptions : ◆ No gas and oil in the aquifer before CO2 breakthrough.
◆ The time lapse neutron log is equivalent the open holeporosity log.

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Geophysical Surveying CO.,LTD.

International Workshop on CO２ Geological Storage , Japan ‘06

Time lapse neutron log calibration
NMR log Vs Time lapse neutron log

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Geophysical Surveying CO.,LTD.

International Workshop on CO２ Geological Storage , Japan ‘06

Porosity Log (OB-2)

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Geophysical Surveying CO.,LTD.

International Workshop on CO２ Geological Storage , Japan ‘06

Change of Porosity (OB-2)

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Geophysical Surveying CO.,LTD.

International Workshop on CO２ Geological Storage , Japan ‘06

CO2 Saturation Map (OB-2)
0.6

0.3

0.0

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Geophysical Surveying CO.,LTD.

International Workshop on CO２ Geological Storage , Japan ‘06

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

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Geophysical Surveying CO.,LTD.

International Workshop on CO２ Geological Storage , Japan ‘06

Conclusions 1Resistivity◆ The resistivity log is good in reproducibility.
◆ CO2 saturation from resistivity is smaller than CO2 saturationfrom neutron log . It is difficult to estimate correct CO2 saturationfrom resistivity on present form. The phase behavior of CO 2 in
the reservoir is still unknown.
Neutron◆ The hydrogen index measurement is easiest and certain way toestimate CO2 saturation.

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Geophysical Surveying CO.,LTD.

International Workshop on CO２ Geological Storage , Japan ‘06

Conclusions 2Acoustic◆ A small amount of CO2 causes a large drop in Vp.
◆ The relation between Vp and CO2 saturation from neutron log
agree with Gassmann theory.
◆ CO2 saturation can be presumed from change of Vp.

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Geophysical Surveying CO.,LTD.

International Workshop on CO２ Geological Storage , Japan ‘06

Jan. 13. 200620
Geophysical Surveying CO.,LTD.

International Workshop on CO２ Geological Storage , Japan ‘06