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.