Risk mitigation through the optimization of residual gas and solubility trapping for CO2 storage in saline aquifers

Abstract

The two most important trapping mechanisms in CO2 storage in saline aquifers, namely residual gas trapping and solubility trapping are examined. It is shown that a water injector located above the CO2 injector can be used to enhance both residual gas trapping and solubility trapping. Using simulation, the optimal location and operating conditions for the water injector are determined for both a low-permeability aquifer and a high-permeability aquifer. It is shown that low vertical permeability and water injection at a larger depth favor residual gas trapping while high vertical permeability and water injection at a smaller depth favor solubility trapping. It is also shown that for high-permeability aquifers, water injection does not increase the total CO2 trapping.