Publications

Geological Carbon Storage (GCS) represents a critical approach in reducing carbon emissions by repurposing dry or depleted oil and gas wells. The objective of this research is to estimate the distribution of pore pressure and fracture pressure within the Talang Akar Formation and how it affects seal integrity for subsurface carbon storage during injection to avoid fault instability which can cause fault reactivation and leakage. Fault seal analysis was conducted on four major faults located in the central area. The Shale Gouge Ratio (SGR) values were relatively low, ranging between 5% and 15%. In contrast, the lower segments of the faults exhibited significantly higher SGR values, ranging from 30% to 65%, indicating substantial sealing potential. Pore and fracture pressure predictions were conducted using the Eaton and Matthews & Kelly empirical method, correlating sonic well log data with pressure and calibrating the results with pressure test data. Subsequently, seismic and well data were integrated to derive pressure distribution within the Talang Akar Formation. The findings of this study show that the Talang Akar Formation is mostly suitable for CO2 injection. However, the lower Talang Akar Formation to the Banuwati Formation in the central Basin reveals signs of overpressure with pressure gradients in the amount of 24.6 kPa/m to 170.9 kPa/m. Fault stability analysis was conducted using the Mohr-Coulomb Failure method, where estimated pore pressure data were used as input to determine the allowable pressure limits required to maintain the stability of fractures and faults. The results of the Mohr-Coulomb analysis indicate that the permissible injection pressure range to ensure the stability of fractures and faults is between 12.9 MPa and 20.2 MPa. These insights provide a basis for evaluating reservoir feasibility and identifying safe and effective carbon storage locations in the Pull Apart Half Graben Complex Basin, Southeast Sumatra.