Effectiveness of seismic detection modelling for CO2 migration scenarios near the Aquistore CO2 injection site, Estevan, Saskatchewan, Canada

The Aquistore site is a proposed CO2 injection site located near Estevan, Saskatchewan, Canada, where CO2 will be stored in a saline aquifer at a depth of approximately 3000 m. This study used fluid replacement modelling to simulate the effects of CO2 migration from the injection interval into overlying saline aquifers. The objective was to discover whether or not, and to what degree, seismic surveys could resolve the presence of CO2 above the injection interval. Log data from a nearby well were analyzed to investigate the effects of adding CO2 on various physical properties of the subsurface. Two sets of synthetic seismic traces - with and without CO2 present - were compared. Differences in traveltimes through aquifer units were also compared before and after CO2 replacement. Results suggest that seismic monitoring at the Aquistore site would be more effective for the detection of CO2 migrating in shallow aquifers than in aquifers near the base of the Williston basin