Study on Cyclic Water Injection Optimization of Wumishan Carbonate Reservoir in Renqiu

The development effect of cyclic water injection field experiment in renqiu wumishan carbonate reservoir is analyzed and summarized by using numerical simulation method. On this basis, the depressurizing amplitude, water injection cycle and development effect of the next stage cyclic water injection are predicted, which can effectively improve the development effect of carbonate reservoir. Research shows that the elastic energy of fluid, the imbibition displacement of hydrophilic rocks and the action of gravity can be used in the process of depressurizing exploitation to exploit the residual oil from the low permeability fracture cavity and rock block, so as to improve the crude oil recovery rate. In terms of depressurizing exploitation mechanism, the larger the wumishan reservoir pressure drop, the more obvious the effect of improving development. Therefore, the reservoir pressure should be reduced as far as possible if condition allowed in depressurizing exploitation. In view of the high reservoir pressure in wumishan carbonate reservoir, the optimal depressurizing exploitation scheme in the early development stage is to maintain the liquid production rate, fully stop injection of water injection wells, and depressurize the reservoir to the ultimate pressure drop. In the late development stage, the shorter the water flooding development time, the larger the reservoir pressure drop, and the better the development effect under the same daily water injection rate. On the contrary, the longer the water flooding development time, the smaller the reservoir pressure drop, and the worse the development effect.