Simulation of long-term geochemical behavior and mineral trapping of CO2 in saline aquifer

Geochemistry plays a significant role in CO₂ storage, especially when considering on long term behavior of injected CO₂. In this work, reactive transport modeling of supercritical CO₂ in a multilayered saline aquifer was performed. After injection for 30 years, the long-term behavior of the CO₂ by considering its geochemical reaction for 5,000 years was investigated. Result shows that mineral trapping occurs mainly within the shale layers. Mineralization becomes the dominant trapping mechanism after 1,000 years. Significant amounts of ankerite precipitate due to the mineralization of the injected CO₂. Calcite dissolved rather than precipitated because of the decrease in pH. Because of the compensation effect among mineral species, precipitation/dissolution around the injection region does not play a significant role to change in porosity and permeability under the geologic conditions employed in this work. The results of this study will be applied to the CCS project that is underway in South Korea.