Abstract: PCS (profile control-surfactant) technology combines profile correction and water plugging with tertiary oil recovery. Based on successful laboratory experiments, optimal oil displacement agent formula that was selected in view of the reservoir conditions in Masai oilfield was used to perform pilot study in Block W95 and W305. Pilot results revealed that the natural decline and composite decline of well groups where PCS had been performed were far less than that of the whole block. Relatively good water-cut control and production stabilization effects were achieved and the economic benefits were remarkable.