Perpustakaan Digital ITB

Carbon Capture and Storage (CCS) is a technique for storing CO2 in underground formations. To prevent CO2 leakage to the surface, four major mechanisms are introduced: structural trapping, residual trapping, dissolution trapping, and mineral trapping. Mineral trapping is a natural trapping processes that ensures injected CO2 stays securely underground. Over hundreds and thousands of years, the CO2 rich fluid reacts with minerals in the rocks to form solid carbonates minerals. The main objective of this study is to investigate the mechanisms and factors influencing CO2 mineral trapping. Pertinent parameters affecting mineral trapping such as porosity, temperature, brine salinity, as well as impurities in injected CO2 were studied. Numerical simulations were performed using a hypothetical compositional reservoir model constructed in CMG Builder, based on an underground depleted gas reservoir located in Japan. The reservoir model was coupled with geochemical reactions involving three minerals (Calcite, Anorthite, and Kaolinite) to simulate mineral dissolution and precipitation. In this simulation, CO2 was injected for 25 years and then the fate of CO2 post-injection period was modeled for the next 225 for base case and 3000 years for extended scenarios. Results indicate that mineral trapping contributes approximately 40.36% to CO2 storage over a 3000-year simulation period, demonstrating its effectiveness despite not being the primary trapping method. Higher porosity enhances CO2 residual and solubility trapping but reduces the potential for mineral trapping. Elevated temperatures consistently accelerate carbonate formation reactions, enhancing CO2 mineralization rates. Salinity significantly impacts solubility trapping, with lower salinity levels favoring greater CO2 dissolution in brine. Minimal influence from H2S impurities on CO2 mineralization, resulting in slight reductions in mineral-trapped CO2 due to lower injected CO2 volumes fraction. Overall, reservoir porosity emerges as the dominant factor that underscores a complex interplay between different trapping mechanisms in geological CO2 storage.