Optimum Salt Concentration Design of Low Salinity Water Injection in Tangai Structure at Sukananti Field

Enhanced Oil Recovery (EOR) come up with promising result to endure mature fields production performance and has been proven worldwide in many various methods. Recently, Low Salinity Water Injection evolves as a simply operation and relatively low cost EOR method with wide of research and implementation seem to be proved effective in the past decades. Some laboratory tests have indicated that injecting low salinity water can improve conventional waterflood performance by 5 – 20%. Hence, it introduces a promising idea that Low Salinity Water Injection should be implemented to mature fields in Indonesia for EOR activity. This paper will focus on determining the optimum salt concentration of injection water for low salinity water injection. Low salinity water injection in this study will be acted as a secondary recovery method. The production performance as a result of low salinity water injection was acquired by numerical simulation using tNavigatorTM Simulator. This simulation will be conducted in Tangai Structure at Sukananti Field, South Sumatera Basin, Indonesia with Talang Akar Formation reservoir target. The simulation is conduct with the constraint injection rate of 1,340 BWIPD. The low salinity water is designed by dilution of salt concentration from formation water with 18,000 ppm of concentration. In this case, the sensitivity of low salinity water, mainly amount of salt concentration design, will be conducted in the simulation consisting of using formation water as scenario’s base case and various low salinity water designs which will be limited until 10x of dilution (1,800 ppm). The result of this study concluded that Low Salinity Water Injection achieved more oil recovery than conventional waterflood did. This incremental is caused by wettability alteration due to of salt concentration changes which attract the clay minerals in reservoir through many complex mechanisms. The simulation result shows that injection water with 10x dilution (1,800 ppm) is chosen as an optimum salt concentration design, which gives the best result with gains additional oil recovery and recovery factor about of 118,8 MSTB and 4,9% respectively from a scenario by injecting formation water (18,000 ppm).