Modeling CO2 Storage in Aquifers with a Fully-Coupled Geochemical EOS Compositional Simulator

Abstract

Abstract This paper describes a fully coupled geochemical compositional Equation-of-State (EOS) compositional simulator for the simulation of CO2 storage in saline aquifers. The simulator (GEM-GHG) models the following phenomena: (1) convective and dispersive flow in porous media; (2) phase equilibrium between the oil, gas and aqueous phase; (3) chemical equilibrium for reactions between the aqueous components and (4) mineral dissolution and precipitation kinetics. For numerical robustness and stability, all equations are solved simultaneously. The simulator is applied to the simulation of typical field-scale CO2 sequestration processes, showing the migration of CO2(g) and CO2(aq), the dissociation of CO2(aq) into HCO− and its subsequent conversion into carbonate minerals. Convection of high-density plumes of CO2-rich brine in conjunction with CO2 mineralization around the plumes is illustrated.