RITE CCS Workshop, 15 Feb. 2007

地中貯留におけるCO2挙動モニタリングについてー 長岡実証試験サイトの実例紹介 ーGeophysical Monitoring of CO2Sequestration in Saline Aquifers-- Lessons from the Nagaoka pilot-scale project -薛 自求 (Xue@rite.or.jp)
Research Institute of Innovative Technology for the Earth

財団法人 地球環境産業技術研究機構

Why CO2 Monitoring ?
Map the movement of CO2 & the CO2 isbeing safely contained within the reservoir.

CO2 sequestration is a safe andverifiable mitigation technology option
Monitoring, Evaluation, Reporting and Verification (MERV)Carbon Dioxide Flooding / CO2-EOR

4 40-70% of CO 2 injected stays in reservoirCanada26

Examples from CO2-EOR &CO2 storage projects
Cross Well Seismic and Electromagnetic (EM)•McElroy oil field, West Texas, USA (Harris et al.,1995)•Lost Hills oil field, South California, USA (Hoversten et al.,2003)

Time-lapse 3D Seismic Survey (4D Seismic)•Weyburn oil field, South Saskatchewan, Canada (White,2004)•Sleipner, aquifer, North Sea, Norway (Art et al., 2004)

Research & Commercial Projects of CO2 Storage

OnshoreFrio(1600 ton)
2 wells

Offshore
Sleipner
Snovhit

Nagaoka, (10400 ton), 4 wells ( one injection & three observation wells
A big research project of CO2 storage at an onshore aquifer.

CO2 Monitoring at Sleipner & Frio

SACS (Saline Aquifer CO2 Storage)
North Sea, Norway (Statoil), Sleipner
Porous Sand
(Net sand:80-100%)
High Permeability(1 - 3 darcy)
Porosity: 35 - 40%

4 - 9.5% CO2

Temp: 37 oC
Pressure: 8 - 11MPa
1 million ton/year(3% of Norway)Seismic Survey at Sleipner

2001
2001

High reflectivity CO2 plume
Chadwick (2004)

Microgravity Survey at Sleipner

Eiken, 2004

( Eiken, 2004 )Frio Brine Pilot Site
( Hovorka, 2006 )••••

Injectioninterval•••

Oil production

Injection interval: 24-m-thick,mineralogically complex
Oligocene reworked fluvial
sandstone, porosity 24%,
Permeability 2.5 Darcys
Steeply dipping 18 degrees
7m perforated zone
Seals − numerous thick shales,
small fault block
Depth 1,500 m
Brine-rock system, nohydrocarbons
150 bar, 53 degrees C,
supercritical CO2

Monitoring at Frio Pilot
Gas
wells

Aquifer wells (4)Determine the subsurface
distribution of injected CO2 using
diverse monitoring technologies

Access tubes, gas sampling( Hovorka, 2006 )DownholeP&T
Wireline
logging
Tracers

Downhole samplingU-tubeGas lift
Radial VSP
Cross wellSeismic, EMthe Nagaoka project &CO2 MonitoringLocation of the Field Test Site for CO2 Injection
Teikoku Oil, Niigata Prefecture(active gas field)

FY2000-2007
byMETI, Japan

Site

RITE (Kyoto)

Tokyo

1000m
2000m

5000m

Overview and Objectives of the Project- A Pilot-scale Demonstration ♦ Improved Understanding of the CO2 Movementin the Porous Sandstone Reservoir► Seismic Wave Velocity Response to CO2 Injection► Mechanism for the Injected CO2 Displacing theFormation Water► Crosswell Seismic Tomography and Well Logging► Measurements of the Formation Pressure Buildup► 3D Surface Seismic Survey► a simulator for the long-term behavior predication► system studies on modeling and public outreachObjectives of time-lapse well logging
and pressure measurement• CO2 breakthrough time (calibrating geological model)• CO2 movements after breakthrough & formationpressure buildup disappeared (driving force and longterm behavior prediction)
Trapping Mechanism• Formation pressure measurements at injection welland one of the three observation wells(pressure buildup due to the low permeability, decay
curves for permeability (single-phase) and relative
permeability (two-phase) estimations)Geophysical Monitoring of CO2 Sequestration
Logging
OB‐4Reservoir Formation Pressure
Formation di60m

p: 1
5°Injection WellLogging

40m
120m

OB‐3Logging

IW‐1aphyrgomoTcieismCross-well S

OB‐2

History of the CO2 Injection at Nagaoka
Fluid sampling
Dec. 2005
Earthquake
Oct.23, 2004

Started
7 July, 2003

Ended1, Jan. 2005

Time-lapse Well Logging
Breakthrough

BreakthroughPost-injection MonitoringLong-term behavior prediction

CO2 Breakthrough time at OB-2 & -4
16th run on May 12 (4,300t-CO2)
No Change

17th run on June 14, (5,400t-CO2)•P-wave velocity : -13%
•Neutron porosity : -6 %OB-3
No Change

No Changes by Now !

OB-4

13th run on Feb. 12 (3,500t-CO2)
No Change

14th logging on Mar. 10 (4,000t-CO2)•P-wave velocity : -28%
•Resistivity : +10%
•Neutron porosity : -10 %

OB-2
IW-1

Sonic Logging @OB-2 (Vp)

End of Injection

Sonic Logging @OB-4 (Vp)

End of Injection

MS2
Results MS1of Crosswell Seismic Tomography

ＭＳ１／ＢＬＳ
ＭＳ１／ＢＬＳ

ＭＳ２／ＢＬＳ
ＭＳ２／ＢＬＳ

２００４／１３，２００ ton

２００４／７
６，２００ ton

ＭＳ３／ＢＬＳ
ＭＳ３／ＢＬＳ

ＭＳ４／ＢＬＳ
ＭＳ４／ＢＬＳ

２００４／１１
８，９００ ton

２００５／１
１０，４００ ton

Geochemical Monitoring– fluid sampling from the reservoir –CO2(sc or gas) Æ CO2 (aq)CO2(aq)+H2O Æ H2CO3Solubility trapping

H2CO3 Æ H+ + HCO3HCO3- Æ H+ + CO32-

Ionic trappingCa2+ + HCO3- Æ CaCO3 + H+Mg2+ + HCO3- Æ MgCO3 + H+Mineral trapping

Fluid sampling

CHDT*(Cased Hole Dynamic Tester)
Arm to fix

DrillFluid Sampling Points at OB-2
1.61108.6m
0.8

Zone-20.0 (Ω・m)

1114.0m

1118.0m-0.8

Fluid samplingOB-2 1114m ： Mostly free CO21108.6m
1114.0m
1118.0m

Gas compositionGas:≒3,500ml

Water:
50ml - 280ml

mol%
H20.00O20.20N20.75

CH40.27

C2H60.00

CO298.78(Contamination 96%)

Sample Chamber(volume 3,786ml)

Fluid samplingOB-2 1108.6m & 1118m ： Water
1108.6m
1114.0m
1118.0m

Gas:
None

Before injection

Water:At 1118m,formation waterrich indissolved CO2.

1108.6m

3430ml-3540ml(Contamination <1%)

1118m
01500

-3000

HCO 3 (ppm)
Sample Chamber(volume 3,786ml)

Fluid samplingOB-2 1108.6m & 1118m ： Ca, Mg & Fe
Beforeinjection
1108.6m

1118m
0400

Ca (ppm)

800015Mg (ppm)

30

0.00

0.75

1.50

Fe (ppm)

At the depth of 1118m (HCO3- conc. increased),concentrations of Ca, Mg and Fe also increased.

Formation Pressure Measurements

Earthquake
Oct.23, 2004

Interpretations on CO2 Monitoring Results
Can we quantify in situ CO2 ?

CO2 saturation?

History Matching on Sonic Vp

Estimation of CO2Saturation
with Gassmann theory

Velocity reduction due tobreakthrough of CO2

Xue et al.,2006

Sonic Vp in Observation Well OB-2 at Nagaoka CO2 Injection Site

1115m2.5
2.3

P-wave velocity vs CO2 saturation

2.1
1.9
1.7

0.0

0.2

0.4

0.6

0.8

1.0

2.7

CO 2 saturation

1116m

2.5
2.3
2.1
1.9
1.7
1.5

0.0

0.2

0.4

0.6

0.8

1.0

CO 2 saturation
2.7▲： estimated from sonic Vp@ OB-2

P-wave Velocity (km/s)

1.5P-wave Velocity (km/s)

P-wave Veloctiy (km/s)

2.71117m

2.5
2.3
2.1
1.9
1.7
1.5

0.0

0.2

0.4

0.6

CO 2 saturation

0.8

1.0

CO2 saturation in OB-2 (from NMR Log)

Conclusion Remarks• Time-lapse crosswell seismic tomography and welllogging data image CO2 clearly.
• CO2 migration pattern depends strongly on theheterogeneity of the sandstone reservoir.
•Successfully applied Gassmann Theory to estimate
CO2 saturation from sonic P-wave velocity.
•Results of CO2 monitoring improved understandings ofCO2 storage and show no evidence of leakage, even in theMid-Niigata Earthquake (M6.8) on October 23, 2004.

ACKNOWLEDGMENTS•This project is funded by Ministry of Economy,
Trade and Industry (METI) of Japan.
•We thank staffs of ENAA, Teikoku Oil Co., OYO Co.,
Geophysical Surveying Co. and RITE involved inNagaoka pilot CO2 injection project.