E EOR method, especially surfactant injection, can be used as a solution toincrease oil recovery in old fields. In this research, the initial stage of selecting thecomposition of the surfactant solution that is suitable or compatible with the salinityof the formation water. This compatibility test aims to filter surfactants that aresuitable for formation water and the phase behavior test is to select surfactants thatform a winsor type III microemulsion so that it can determine the optimum salinityof the surfactant. In this study, 15 compositions of Cemara Wood SLS surfactantwere used with compatibility test concentration ranges of 0.5%, 0.75%, 1%, 1.25%,1.5%, 2%, 2.5%, 3%, 3, 5% and 4% with formation water variations of 90,000 ppm,120,000 ppm and 125,000 ppm.The results of the study using intermediate crude oil obtained the bestresults in the middle phase behavior test, namely at a salinity of 90,000 ppm, aconcentration of 3.5% had 11.3% stable microemulsion and a salinity of 120,000ppm, a concentration of 1.25% had 12.5% stable microemulsion, so that both Thiscomposition will be used in coreflood activities on 2 synthetic Core Berea with 19%porosity and permeability between 380-400 mD to determine the difference inrecovery factor results.The results of the coreflooding test obtained an additional value of 1.28%SLS surfactant recovery factor with a 120,000 ppm salinity surfactant solution witha concentration of 1.25% and a recovery factor of 1.22% with a 90,000 ppmsurfactant salinity solution with a concentration of 3.5% with the core holderposition vertically on the coreflood of both cores.