Numerical Simulation of CO₂ Mineral Trapping Potential of Carbonate Rocks

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.