Optimalisasi Kinerja Teknologi Enhanced Oil Recovery Hybrid Thermal-CO2 Berdasarkan CSOR dan Recovery Factor Lapangan X

Abstract

Field X is a heavy oil reservoir with an API gravity of 22°API and a viscosity of 248 cP, resulting in low oil mobility and suboptimal recovery through conventional production methods. The development of Thermal-CO₂ EOR technology has shown promising results in various international heavy oil fields, serving as the basis for research and development at Field X. This study aims to compare the performance of the base-case scenario, pure steamflooding, and hybrid thermal–CO₂ EOR; analyze the effect of CO₂ concentration on the cumulative steam-oil ratio (cSOR), recovery factor, and sweep efficiency; and determine the optimal CO₂ concentration. Reservoir simulations were conducted over the 2020–2040 forecasting period. The EOR scenarios utilized six injection wells with an injection rate of 628,981 Stb/day per well, a temperature of 100°C, a pressure of 14.7 psi, and a steam quality of 0.8. The hybrid thermal-CO₂ scenario was conducted with the same total injection rate, varying the CO₂ concentration at 5%, 10%, 15%, 20%, and 25%. Volumetric sweep efficiency was estimated using the relationship between the recovery factor, displacement efficiency, and changes in water saturation, with an initial oil saturation of 0.41818. Simulation results show that the basecase yields a cumulative production of 4,176 MMSTB and an RF of 27.637%. Pure steamflooding increased cumulative production to 5,817 MMSTB and RF to 38.492%, but resulted in a cSOR of 4,886. A CO₂ concentration of 10% provided the best performance with a cumulative production of 6,035 MMSTB, an RF of 39.937%, a cSOR of 4,253, and a volumetric sweep efficiency of 67.47%. Although the 25% concentration yielded the lowest cSOR of 3,655, it had lower RF and sweep efficiency. Thus, a 10% CO₂ concentration was determined to be the technically optimal condition, as it provided the best balance between increased oil recovery, reduced steam consumption, and improved sweep efficiency.