Processing and Interpretation of Time-lapse Vertical Seismic Profile Data from the Penn West CO₂ Monitoring Project

Marcia L. Couëslan

At the Penn West CO₂ Pilot Project in Central Alberta, CO₂ is being injected into the Cardium Formation at a depth of 1620 m in the Pembina Oil Field for enhanced recovery and carbon storage purposes. The reservoir is being monitored using simultaneously acquired time-lapse multicomponent surface and vertical seismic profile (VSP) surveys. These provide lateral coverage of the survey area as well as high-resolution images near the observation well. The baseline survey was acquired in March 2005 prior to CO₂ injection, and the first monitor survey was acquired in December 2005. Both the P-wave and Sv-wave VSP images show excellent ties with the P-wave surface seismic data and have higher frequency bandwidth and resolution. 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 at the base of the reservoir on one of the walkaway lines.