Time-lapse Monitoring of CO2 EOR and Storage with Walkaway VSPs

Summary At the Violet Grove pilot project, 100 km southwest of Edmonton, Alberta, CO2 is being injected into the Cardium Formation in the Pembina Oil Field for enhanced recovery and carbon sequestration purposes. The reservoir is being monitored using simultaneously acquired time-lapse multicomponent surface and borehole seismic surveys. The baseline survey was acquired in March 2005 prior to CO2 injection. The first monitor survey was acquired in December 2005 after eight months of CO2 injection. The borehole seismic data displays higher bandwidth and increased resolution than the surface seismic data. Comparisons between the baseline and monitor borehole seismic surveys show an increase in reflectivity at the reservoir, and crosscorrelations show a time shift of 0.2 ms on two of the walkaway lines.