Diffusive and Convective Transport of Disposed CO_2 in Porous Media: A Numerical Approach

摘要

Geologic Carbon Storage (GCS) is one the most promising methods for stabilizing the atmospheric CO_2 concentration, and one challenging problem at this point is the prediction of the long-term transport phenomena of disposed CO2 in the geologic time scale. While small pore size of sealing formations overlying a CO_2-injected layer hinders CO_2 movement in a liquid or supercritical phase, CO_2 dissolved in an aqueous phase will be transported by diffusion and convective flow in porous media. This study explores the diffusive and convective transport of dissolved CO_2 in porous media. Governing equations for modeling two-dimensional CO_2 transport problems were reviewed, and the system of equations was solved using Finite Element (FE) method. Our FE model was validated with published Hele-Shaw experiment results, and the transport of dissolved CO_2 in porous media was well captured with our numerical model. Additional different cases were simulated to examine the effects of CO_2 concentration profile at the interface between CO_2 and pore water. In addition, the effect of the heterogeneity in permeability, the initiation time of convection, and the dissolution rate of CO_2 were discussed.