Time-lapse seismic modeling of CO₂ sequestration at Quest CCS project

Shahin Moradi, Donald C. Lawton

A time-lapse analysis was carried out to investigate the theoretical detectability of CO₂ for the Shell Quest project. Quest is a Carbon Capture and Storage (CCS) project in Alberta conducted by Shell Canada Energy, Chevron Canada Limited, and Marathon Oil Canada Corporation. The target formation for injection is Basal Cambrian Sandstone (BCS) which is a deep saline aquifer at an approximate depth of 2000 meters below surface. The purpose of this study was to simulate the seismic response of the BCS after injecting 1.2 million tonnes of CO₂ during a one-year period of injection. This was done using Gassmann fluid substitution and seismic forward modeling. A geological model for the baseline scenario was generated based on data from well SCL- 8-19-59-20W4. For the monitor case, Gassmann fluid substitution modeling was undertaken to model a CO₂ plume within BCS. Numerical stack sections for both scenarios were obtained and subtracted to study the change in the seismic response after injecting CO₂. The difference section shows the location and the spacial distribution of the plume. Based on these results the CO₂ plume could be detected in the seismic data after a year of injection.