Oil recovery reduction obviously happened on mature reservoir. In consequence, at a time when the economic recovery is threatened by potentially high crude oil prices due to increased demand, it needs an effort to gain those remaining oil. One of the efforts is with Enhanced Oil Recovery process using surfactant flooding method. The expensive price of surfactant still becomes a barrier for the usage of surfactant flooding process on a macro scale. Therefore, this study purpose is to evaluate the effect of drainage area on surfactant flooding process and determine the optimum area that can give the maximum financial
profit. This study includes a simulation of surfactant flooding process and economic analysis for simulation result. In the end, it is obtained from this study that the optimum drainage area for surfactant flooding method is within a range of 50-125 acres.