Numerical Simulation of CO2 Mineral Trapping Potential of Carbonate Rocks

Abstract

During CO2 geo-storage, mineral dissolution is considered as the safest trapping technique however it is the longest and the most complicated trapping mechanism involving geo-chemical reactions and physical forces like diffusion and advection. Many factors also influence the mineral trapping capacity of the geological formation e.g., mineralogy, temperature, pH, CO2 fugacity, pressure of CO2, salinity and impurities. The scope of this study is to investigate the mineral trapping of CO2 in Arabian carbonates reservoirs as a function of CO2 pressure injection, presence of contaminants and well configuration. Numerical simulations were performed using the multi-phase simulator GEM-CMG. 2D and 3D models were developed to examine the mechanisms occurring during mineral trapping and how these affect its efficiency. The mineralogy of a carbonate field from an Arabian formation was used. Sensitivity analysis was performed on the above variables on CO2 mineralization tendency. The results suggest that dissolution and precipitation of minerals occurred during and post CO2 injection. Increasing pressure led to higher amount of CO2 trapped while the presence of impurities in the injected fluid reduced the potential of CO2 mineralization. Moreover, using horizontal well tends to promote the mineral activity during CO2 storage. While a score of publications investigated CO2 storage via structural, residual and dissolution trapping mechanisms, still the mineral trapping potential and its influencing factors have not been investigated much. This paper thus provides insights into CO2 sequestration by mineral trapping pertinent to Arabian carbonate rocks.