Integrated geophysical and geochemical research programs of the IEA GHG Weyburn-Midale CO2 monitoring and storage project

AbstractCommercial-scale CO2 injection has continued at the Weyburn field in Saskatchewan since 2000 as part of EnCana’s enhanced oil recovery (EOR) project. As of Sept. 30, 2008, a total of 18 megatonnes of CO2 had been injected of which ∼11 megatonnes remains (stored) in the reservoir. Geophysical and geochemical research activities carried out during Phase I (2000-2004) of the IEA Weyburn Project’s Monitoring, Measurement and Verification (MMV) program have been continued and augmented during the Final Phase (2007-2011) and interim period. CO2 migration within the reservoir is tracked using several geophysical techniques, including 4D multi-component seismic monitoring at intervals of 12-36 months and continuous subsurface passive recording of microseismic activity. Compositional evolution within this dynamic spatial framework is monitored by sampling and geochemical analysis of production fluids every 6 months, while potential CO2 seepage to the surface is assessed through analogous time-lapse monitoring of shallow groundwater and soil gas. Additional key components of the Final Phase research program include discriminating pressure and fluid saturation effects in the seismic data through shear-wave data processing and inversion of amplitude versus offset information, forecasting dynamic CO2 mass partitioning and long-term storage containment efficacy through reactive transport simulation, and evaluating the impact of CO2 impurities and mineral trapping on reservoir/seal integrity through experimental work. Finally, the 4D seismic reflection and fluid chemistry data will be fully exploited to improve site characterization and dependent predictions of CO2 storage performance using a novel stochastic inversion technique that integrates geophysical/geochemical monitoring and modeling activities