Modeling supercritical CO2 injection in heterogeneous porous media

We investigate the physical processes that occur during the sequestration of CO{sub 2} in brine-bearing geologic formations using TOUGH2. An equation of state package that treats a two-phase (liquid, gas), three-component (water, salt, and CO{sub 2}) system is employed. CO{sub 2} is injected in a supercritical state that has a much lower density and viscosity than the liquid brine it displaces. In situ, the supercritical CO{sub 2} forms a gas-like phase, and also partially dissolves in the aqueous phase. Chemical reactions between CO{sub 2} and rock minerals that could potentially contribute to mineral trapping of CO{sub 2} are not included. The geological setting considered is a fluvial/deltaic formation that is strongly heterogeneous, making preferential flow a significant effect, especially when coupled with the strong buoyancy forces acting on the gas-like CO{sub 2} plume. Key model development concerns include vertical and lateral grid resolution, grid orientation effects, and the choice of characteristic curves