Compositional reservoir simulation study for gas cap CO2 injection plan in the A-1 layer of "Jupiter" field

The "Jupiter" field is located in South Sumatera with Talang Akar Formation as the main reservoir and consists of Layers A, B, and C. Layer A is divided into three sub-layers (A-1, A-2, and A-3). In the previous research in Layer A, some development wells and water injection wells had been planned (Farah, S. N., 2016) and used as a Base case. Then the Base case was added with four CO2 injection wells (immiscible and miscible) in the oil zone of the A-1 Layer (Ma'roefi, Rambu Muhammad., 2019). This study will simulate with gas cap CO2 injection to compare with CO2 injection in the oil zone and only focuses on the A-1 sub-layer. The method used in this study was reservoir simulation using CMG GEM Version 2012 simulator. The best scenario was determined by sensitivity of the best injection pattern, the best rate, and the best injection pressure. Based on the simulation results, it is shown that the injection pattern is not so affecting in determining the success of gas cap CO2 injection, the optimum variety of injection rate is 2570 MSCFD, and the optimum pressure is 679 psi. Scenario III-B is more optimum than the best immiscible scenario and would be more optimum if usage of the miscible CO2 scenario, which could give the recovery factor 9.23%.