Coupling Mass Transfer with Mineral Reactions to Investigate CO₂ Sequestration in Saline Aquifers With Non-Equilibrium thermodynamics

Abstract

Abstract:The coupling behaviors of mass transfer of aqueous CO 2 with mineral reactions of aqueous CO 2 with rock anorthite are investigated by chemical potential gradient and concentration gradient models, respectively. SAFT1-RPM is used to calculate the fugacity of CO 2 in brine. The effective diffusion coefficients of CO 2 are obtained based on the experimental kinetic data reported in literature. The calculation results by the two models and for two cases (mass transfer only and coupling mass transfer with mineral reaction) are compared. The results show that there are considerable discrepancies for the concentration distribution with distance by the concentration gradient and chemical potential gradient models, which implies the importance of consideration of the non-ideality. And the concentrations of aqueous CO 2 at different distances by the concentration gradient model are higher and further than that by the chemical potential gradient model. The mineral reaction plays a considerable role for the CO 2 geological sequestration when the time scale reaches 10 years for the anorthite case.