Perpustakaan Digital ITB

Oil and gas operations contribute approximately 15% of global energy-related emissions, amounting to 5.1 billion tonnes of greenhouse gases annually (IEA, 2021), highlighting the urgent need for mitigation strategies such as Carbon Capture and Storage (CCS). Among various CO? trapping mechanisms, mineral trapping offers a more permanent solution by chemically converting CO? into stable solid minerals. This study investigates the contribution of mineral trapping across saline aquifers, depleted gas reservoirs, and depleted oil reservoirs through numerical simulations performed using tNavigator. Three synthetic compositional models representing each storage formation were developed, with reservoir dimensions of 20,476 ft × 20,398 ft × 547 ft, discretized into a uniform grid of 31 × 31 × 22 cells. Geochemical interactions were modeled by incorporating three equilibrium CO? dissolution reactions and one mineral precipitation reaction to simulate calcite (CaCO?) formation. CO? injection was carried out over a 2-year period, with a total injected volume of 37.5 BSCF, followed by a 1000-year post-injection simulation. Mineral trapping was found to be minimal: 0.0006% in saline aquifers, 0.0002% in depleted gas reservoirs, and none in depleted oil reservoirs. Calcite formation reached 25 tonnes in saline aquifers and 10 tonnes in depleted gas reservoirs. Among all formations, saline aquifers exhibited the highest total CO? trapping, comprising 89.4% residual, 3.3% solubility, and 6.8% structural CO?. Depleted gas reservoirs demonstrated 53.5% residual and 45.3% structural trapping, while depleted oil reservoirs retained 31% residual, 37% CO? dissolved in oil, and 32% structural trapping. The primary influencing factor identified in this study was initial fluid saturation. Saline aquifers, being fully watersaturated, facilitated extensive CO?–brine interactions, thereby enhancing dissolution and mineralization. Conversely, the presence of residual hydrocarbons in depleted reservoirs limited CO? dissolution, with the effect being more pronounced in depleted oil reservoirs due to CO?–oil miscibility. Mineral trapping should therefore be considered in saline aquifers and depleted gas reservoirs where mineral precipitation occurs, whereas its impact is negligible in depleted oil reservoirs where no mineral formation was observed.