WBPC 2019 Abstract #11
The Aquistore Project, located near Estevan, Saskatchewan, has been injecting CO2 since 2015 at average rates of ~45,000 tonnes per year. CO2 injection is occurring over several intervals within the Winnipeg Black Island Member and the Deadwood Formation at 3150-3350 m depth. 4D seismic monitoring has been conducted at the Aquistore site using a permanent 2D array of surface geophones and with distributed acoustic sensing (DAS) utilizing a 2700 m fibre-optic cable cemented in an observation well. 4D surface and vertical seismic surveys have been acquired at times when cumulative injected CO2 was 36, 102 and 141 kilotonnes, respectively.
Time-lapse amplitude differences observed in the resultant 3D seismic images are interpreted as zones of CO2 saturation. At 36 kilotonnes of CO2 injected, a plume is observed in the upper Deadwood interval that extends a maximum of 150 m from the injection well. In images corresponding to 102 and 141 kilotonnes of CO2 injected, the area of this plume increases by at least a factor of two, and a smaller plume appears to be developing in the lower Deadwood. The CO2 generally appears to be migrating from the injection well in the regional up-dip direction (NNW) following subparallel structural and porosity/permeability fabric in the reservoir. Results from the 4D seismic analysis are compared against in situ measurements of CO2 distribution in the injection well (flow rates at the injection intervals) and time-lapse CO2 saturation logs from the observation well.