CO[subscript 2] migration in saline aquifers: Regimes in migration with dissolution

Abstract

We incorporate CO[subscript 2] dissolution due to convective mixing into a sharp-interface mathematical model for the post-injection migration of a plume of CO[subscript 2] in a saline aquifer. The model captures CO[subscript 2] migration due to groundwater flow and aquifer slope, as well as residual trapping and dissolution. We also account for the tongued shape of the plume at the end of the injection period. We solve the model numerically and identify three regimes in CO[subscript 2] migration with dissolution, based on how quickly the brine beneath the plume saturates with dissolved CO[subscript 2]. When the brine saturates slowly relative to plume migration, dissolution is controlled by the dimensionless dissolution rate. When the brine saturates “instantaneously” relative to plume migration, dissolution is instead controlled by the solubility of CO[subscript 2] in brine. We show that dissolution can lead to a several-fold increase in storage efficiency. In a companion paper, we study migration and pressure limitations on storage capacity [Szulczewski et al., GHGT-10, Paper 917 (2010)].