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Geophysical Monitoring at the Weyburn CCS/EOR Project : 

Geophysical Monitoring at the Weyburn CCS/EOR Project James Verdon James.Verdon@bristol.ac.uk Trans-Atlantic Research to Business: CCS in EOR Houston, TX 05.12.2011

The Weyburn Oil Field : 

The Weyburn Oil Field Located in Saskatchewan, Central Canada Size = 70 miles2 Original Oil In Place = 1.4 billion barrels Production began in 1955 Oil recovered so far = 370 million barrels (26%) Extra Oil Recovered by CO2 Injection = 130 million barrels (10%) CO2 supplied from goal gasification plant, North Dakota.

The Weyburn Oil Field : 

The Weyburn Oil Field

CO2 Storage Capacity : 

CO2 Storage Capacity

The Weyburn Reservoir : 

Reservoir found in Palaeozoic rocks. Upper dolostone and lower limestone zones. 30m thick in total. Caprocks: an evaporite overlain by shale. The Weyburn Reservoir

EOR Area : 

EOR Area

Geophysical Monitoring: Aims : 

Monitoring has two main goals: Accounting: Image the CO2 volume, distribution and concentration within the reservoir Risk assessment: Detect leakage (and potential leakage pathways) from the reservoir Also interested in: Model verification Reservoir integrity Efficiency of storage Geophysical Monitoring: Aims

Slide 8: 

Time-lapse seismic surveys have formed the backbone of the geophysical monitoring program at Weyburn. Regular time-lapse seismic monitoring surveys have been conducted to image the CO2 plumes - 1999, 2002, 2004, 2007. Surveys image changes in reflection amplitudes and travel times. Substitution of brine/oil by CO2 reduces the P-wave velocity, which affects R and TT. VP dVP R1 R2 TT1 TT2 Caprock Reservoir Time Lapse Seismic Reflection

Slide 9: 

Baseline Survey: Repeat Survey: Repeat – baseline: Time Lapse Seismic Reflection

Slide 10: 

Caprock Watrous Vanguard Colorado Baseline Survey: Reservoir 3 2 1 Time Lapse Seismic Reflection

Slide 11: 

Accounting: Spatial distribution of time-lapse amplitude anomalies: 2.8 MT CO2 3.7 MT CO2 7.4 MT CO2 Time Lapse Seismic Reflection

Slide 12: 

2.8 MT CO2 3.7 MT CO2 Accounting: Spatial distribution of time-lapse travel-time anomalies: Time Lapse Seismic Reflection

Slide 13: 

However, the big question remains – how to quantify this change? Time Lapse Seismic Reflection

Slide 14: 

Risk Assessment: Spatial distribution of travel-time anomalies: Reservoir Above Reservoir Above Regional Seal Time Lapse Seismic Reflection

Slide 15: 

Risk Assessment: Spatial distribution of amplitude anomalies: Reservoir Reservoir + 20m Reservoir + 50m Time Lapse Seismic Reflection

Slide 16: 

Cause of OOZ Anomolies: Seismic artifacts (non-repeatability) Stress changes Pressure communication with reservoir Out-of-zone CO2 Time Lapse Seismic Reflection

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Fracturing induced by injection can be tracked by monitoring the ‘microearthquakes’ created. Events are located using the same methods as developed in global/regional seismology. Microseismic Monitoring

Slide 18: 

Events are located in and above the reservoir Events located around production wells rather than injection point Events are best interpreted alongside geomechanical modelling studies Only one pattern is covered by microseismic arrays Microseismic Monitoring

Slide 19: 

D.J. White (NRCan) M. Meadows, S. Cole (Fugro Seismic Imaging) A. Ramirez, Y. Hao, S. Carle (Lawrence Livermore National Lab) A. Duxbury, C. Samson (Carleton University) B. Dietiker (Petroleum Technology Research Centre) J. Johnson (Schlumberger-Doll Research) I. Morozov (University of Saskatchewan),

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http://www1.gly.bris.ac.uk/BUMPS/ http://www1.gly.bris.ac.uk/~JamesVerdon/ http://www1.gly.bris.ac.uk/BCOG/