Perpustakaan Digital ITB

Facing the accelerating growth of energy demand, oil and gas industries play an important role to ensure its fulfillment. One way is through the EOR (Enhanced Oil Recovery) method. One of the EOR methods being researched and developed is Low Salinity Water Injection (LSWI). LSWI has a potential for oil recovery of 5-20% as secondary recovery in sandstone reservoirs. Researches regarding LSWI optimization are highly promising with many ideas for refinement. One of the ideas in optimizing the LSWI method is adding a polymer solution into the LSWI. This study was conducted to study the use of a combination between LSWI and polymer. Other than that, combination of LSWI and polymer is considered as one of pilot project prospective to be implemented in Indonesia. This research was conducted by designing a combination model of LSWI and polymer to be applied in a sandstone reservoir in the “B” Structure in the “S” Field, South Sumatra, Indonesia. Reservoir simulation and production forecasting were performed using the Computer Modeling Group (CMG) simulation software, which included history matching, forecasting, and sensitivity analysis. The sensitivity analysis performed on the parameters that affect the simulation results, there are salinity, polymer concentration, and injection rate. The simulation time used is 14 years of the production period from December 2020. This study conclude that oil recovery factor insignificantly increases up to 1.8 % using the lower salinity of the injected water, i.e., 3600 ppm to 1800 ppm, due to a slight difference of equivalent ion fraction between the salinities, while the optimum recovery is achieved by using 50 wt% of polymer concentrations in the number of 59.21%. Meanwhile, the higher polymer concentration causes oil recovery to decrease because higher polymer concentration causes the viscosity of the polymer to become very viscous that yields ineffective sweep to the remaining oil. The scenario in which combination of 1800 ppm of salinity and 50 wt% of polymer concentration is injected at 1000 bbl/day gives an additional recovery factor of about 8% from the base cases which is the best result for this case study. Therefore, the combination injection of low salinity water with polymer is recommended to be applied at “B” Structure in “S” Field for further development.