Computer simulation of CO 2 trapped through mineral precipitation in the Rose Run Sandstone, Ohio

Abstract

Equilibrium, path-of-reaction and kinetic modeling of CO 2–brine–mineral reactions in the Rose Run Sandstone, one of Ohio’s deep saline aquifers, was conducted in order to investigate the factors that are likely to influence the capacity of this formation to trap injected CO 2 as solid carbonate mineral phases. Equilibrium modeling was applied to investigate the impact of temperature, pressure, mineralogy, brine composition, and CO 2 fugacity on mineral dissolution and precipitation, the amount of CO 2 sequestered, and the form of sequestration. Path of reaction and kinetic modeling were used to evaluate intermediate products and reaction progress as a function of time, as well as to investigate the impact of brine-to-rock ratio. The results of equilibrium modeling demonstrate that dissolution of albite, K-feldspar, and glauconite, and the precipitation of dawsonite and siderite are potentially very important for mineral trapping of CO 2. According to the path of reaction and kinetic modelling, the stability of carbonate rocks is controlled by the brine-to-rock ratio, the pH of the system, the fugacity of CO 2, and the kinetic rate of dissolution. In kinetic modeling, with a brine-to-rock ratio of 1:25, reactive surface area of 10 cm 2/g, 10 MPa f CO 2 , and 12% porosity (1.5–2 g of CO 2 per kg of reacted rock), significant quantities (10–40 g) of carbonate minerals were precipitated from both the sandstone and mixed rock assemblages. The Rose Run Sandstone has the potential to store CO 2 over millennia as a negatively buoyant aqueous solution and, ultimately, as immobile carbonate minerals.