Grey decision-making theory in the optimization of strata series recombination programs of high water-cut oilfields

The development performance of bedded sandstone reservoirs by water drive become worse year by year after entering the high water-cut stage. Optimization and recombination of the strata series based on reservoir subdivision is an effective way to improve water injection effect and to increase producing level. This paper uses the mono-objective grey situation decision-making method, combines various indexes and the expert experiences reflecting reservoir development performance, introduces the concept of effect factors to consider various factors which reflect the contradictories of reservoir strata series, such as permeability differentials, single layer water flooding degree, producing level, remaining amount of resources, hole interval length and the amount of oil layer, to create measurement matrix for comprehensive effects and then to work out the optimal solution of strata recombination programs. Case analysis and comparison with the reservoir numerical simulation result showed that, the grey decision-making optimization method has reliable results, can effectively solve the contradiction between of the efficiency and effect, and can help to guide the development and adjustment of bedded sandstone reservoirs by water drive during the high water-cut stage.