2-D reactive transport modeling of the fate of CO2 injected into a saline aquifer in the Wabamun Lake Area, Alberta, Canada

Abstract Carbon capture and storage (CCS) is a viable option to reduce emissions of anthropogenic CO 2 into the atmosphere. One important component during the storage site selection process is the prediction of the movement and the fate of the injected CO 2 in the chosen reservoir. The fate of CO 2 injected into a saline aquifer of the Devonian Nisku Formation in Alberta (Canada) was simulated using the reactive transport code TOUGHREACT. A 2D radially symmetric model was developed for a 50-year CO 2 injection phase followed by a 1000-year storage period. CO 2 was injected into the bottom 10 m of the Nisku Formation at a rate of 1 Mton/year for 50 years. The injected supercritical CO 2 spread out radially up to 3.5 km after 50 years of injection and 6.0 km after 1000 years of post-injection. After 1000 years, the injected CO 2 was trapped in the Nisku Formation underneath the excellent seal of the Calmar shale predominantly as free CO 2 via hydrodynamic trapping (76%) and to a lesser extent by solubility trapping (23%) in aqueous phase ( HCO 3 - ( aq ) ). Mineral trapping of injected CO 2 in the Nisku aquifer was negligible. This study predicted the interactions of the fluids and rock minerals with injected CO 2 in the storage Nisku aquifer, the Calmar caprock and the bottom rock Ireton shale. This information will be highly beneficial for potential future CO 2 injection projects targeting the saline aquifer of the Nisku Formation in Western Canada.