SIMULATION OF IMPORTANT PROCESSES IN CO_2 STORAGE IN AQUIFERS

摘要

This paper describes the modelling of important processes in CO_2 storage in saline aquifers with a fully coupled geochemical Equation-of-State (EOS) compositional simulator. The simulator (GEM-GHG™) models the following phenomena: (1) convective and dispersive flow in porous media; (2) gas solubility in the aqueous phase; (3) chemical equilibrium reactions between the aqueous components; (4) mineral dissolution and precipitation kinetics and (5) leakage through the cap rock and through sealing faults. The simulator is applied to the simulation of typical field-scale CO_2 sequestration processes, showing the migration of CO_2(g) and CO_2(aq), the dissociation of CO_2(aq) into HCO_3~-, and its subsequent conversion into carbonate minerals. Convection of high-density plumes of CO_2-rich brine in conjunction with CO_2 mineralization around the plumes is illustrated. A typical run showing the leakage through sealing faults is also described.