A systematic integrated approach for waterflooding optimization

In near offshore oil fields, drilling and platform construction costs are high. Therefore, waterflooding optimization becomes the cheapest and most effective method to enhance project economics and consequently receive considerable attention. In this paper, a systematic approach was proposed to automatically determine well placement and operation constraints. The well-placement was optimized through an efficient ranking-based method which consisted of two stages. In the first stage, it was assumed that every column of cell in the reservoir simulation model contained a producer. Through iterative simulation, the most effective producers were identified by applying the screening criteria to maximize the oil production. In the second stage, the injector-placement was determined based on the dynamic injection allocation and volumetric sweep efficiency of waterflooding patterns through streamline numerical simulation. This ranking-based well-placement optimization method was validated by two examples. The results suggest that this method is very efficient and effective. Also, the adjoint-based optimization algorithm was employed to optimize the water injection rate for each injector and the liquid production rate for each producer. This systematic waterflooding-optimization approach was applied to manage NP1-29 Block, a near offshore faulted reservoir in China. After the optimization, 10-year oil production increased about 16% over the conventional waterflooding design. •Two-stage optimization strategy was proposed to optimize the well-placement.•Ranking method, black oil and streamline simulation were integrated in optimization.•Adjoint-based gradient optimization method was used to optimize the operation rates.•Using proposed strategy can improve cumulative oil production greatly.