(481e) Geo-Chemo-Mechanical Studies for Permanent CO2 Storage in Geologic Reservoirs

Increasing concentration of CO₂ in the atmosphere is attributed to rising consumption of fossil fuels around the world. The development of solutions to reduce CO₂ emissions to the atmosphere is one of the most urgent needs of today’s society. CO₂ injection into geological formations is one of the CO₂ storage options with a large capacity. If non-carbonate minerals such as basalt and olivine exist in the CO₂ injection site, the injected CO₂ can react with those minerals to form thermodynamically stable solid carbonates. In nature, mineral carbonation takes place via dissolution of the mineral to release Ca/Mg ions followed by precipitation of Ca/Mg in the presence of CO₂. The rate limiting step of this carbon mineralization process is considered to be the dissolution of the mineral.A question has been raised regarding the effect of in-situ carbon mineralization on the stability of the geologic storage of CO₂. Both the kinetics and extents of mineral dissolution and carbonation reactions within the geological reservoir are important factors to evaluate for the long term stability of the geologically injected CO₂.Therefore, this work focuses on understanding CO₂-mineral-water interactions at a wide range of reaction conditions (T_max = 200^­oC and P_{CO2, max} = 200 bar). Both deionized water and synthetic brine were used as the aqueous reaction media. Minerals such as olivine (Mg₂SiO₄), labradorite ((Ca,Na)(Al,Si)₄O₈) and basalt (mixture of silicate minerals), were selected based on their abundance in nature and both dissolution and single-step carbonation experiments were performed to investigate fast and long-term kinetics of mineral weathering. Two different regimes (i.e., surface reaction vs. mass transfer limited regimes) of mineral weathering were identified based on the analyses of the activation energy and reaction kinetics.