Reservoir Simulation Modeling With Polymer Injection in Naturally Fractured Carbonate Reservoir

Abstract

Naturally fractured carbonate reservoirs (NFCR) generally have very large residual reserves and are suitable for advanced production stages, where oil recovery in the Naturally fractured carbonate reservoir can be carried out by polymer injection. This study uses a hypothetical model using 5 wells, where during the initialization it has an Original Oil In Place (OOIP) of 12.129 MMSTB. The reservoir simulation was performed at basecase and showed a Recovery Factor (RF) of 8% with cumulative production of 973.66 MSTB. This recovery factor is the reason why polymer is used, the working mechanism of the polymer is by reducing the mobility ratio so that the viscosity of the water will increase and be able to sweep away the oil that is still left in the reservoir rock. There are 5 scenarios used in this study, where each scenario has different concentrations of 50 lb/d, 100 lb/d, 150 lb/d, 150 lb/d, 200 lb/d, 250 lb/d, respectively, then each scenario is tested with different rates in a succession of 500 bbl/day, 750 bbl/day, 1000 bbl/day, 1250 bbl/day, 1500 bbl/day, but the pattern of each scenario is the same as using an inverted-5-spot pattern. From all the scenarios, the best scenario is the third scenario, namely using a polymer concentration of 150 lb/d and a rate of 1250 bbl/d which can increase recovery factor from 10.81 to 18.81% with cumulative production of 2.282 MMSTB.