Modeling the Sequestration of CO2 in Deep Geological Formations

Modeling the injection of CO 2 and its sequestration will require simulations of a multi-well injection system in a large reservoir field. However, modeling at the injection well scale is a necessary prerequisite to reservoir scale modeling. We report on the development and application of two models: 1) a semi-analytical model (PNLCARB), and 2) a numerical model (STOMP-CO 2). PNLCARB can simulate multiphase, radial injection of CO 2 and the growth of its area of review around the injector, buoyancy-driven migration of CO 2 toward the top confining layer, and dissolution of CO 2 during injection and vertical migration. Phase behavior algorithms for the physicochemical properties CO 2 , including the supercritical region, were also added to the Subsurface Transport Over Multiple Phases (STOMP) simulator. The models effectively simulate deep-well injection of water-immiscible, gaseous, or supercritical CO 2. The effect of pertinent fluid, reservoir, and operational characteristics on the deep-well injection of CO 2 was investigated. Results indicate that the injected CO 2 phase initially grows as a bubble radially outward, dissolves partially in the formation waters, and eventually floats toward the top confining layer due to buoyancy effects. Formation permeability, porosity, injection rate and pressure, and dissolution of CO 2 influence the growth and ultimate distribution of the CO 2 phase.