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ABSTRAK Dezatama Thabay Iwary
PUBLIC Suharsiyah

Field D, located in Indonesia’s offshore Mahakam Delta, is a mature oil and gas field with secondary and tertiary recovery potential due to abundant water sources. The field was discovered in 1972. The objectives of this study were to compare waterflooding and alkaline-surfactant-polymer (ASP) flooding as EOR methods based on recovery factors and cost expenses. The study utilized a conventional reservoir simulator and generated a model through initialization, history matching, and forecasting. The results show that ASP flooding was the most efficient method for increasing the estimated ultimate recovery and decreasing the production decline rate. The alkalisurfactant- polymer case is estimated to recover hydrocarbon by 27.61 MMBO, or 10.72% incremental gain, 3.38 MMBO more than a waterflood case, by the end of the contract in 2038. The strong aquifer in field D is a significant factor that makes ASP flooding technically feasible and meets the screening table’s parameters: hydrocarbon, aquifer, and reservoir. Economic calculations showed that implementing ASP flooding was feasible with a Net Present Value of $3.43 million, a Pay Out Time of 5 months, and an Internal Rate of Return of 15.3%. Thus, it is recommended that ASP flooding should be considered a viable option for improving oil recovery in the mature offshore field.