复杂小断块油藏水驱辅助注气吞吐提高采收率研究

复杂小断块油藏单纯利用注水或注气措施难以兼顾整个剩余油区域,挖潜效果有限。为提高复杂小断块油藏高含水期剩余油采收率,运用数值模拟方法探索了水驱辅助注气吞吐的开发方式,同时利用经济和效率双重指标分析了其油藏适应性。依据不同措施方案下典型模型的开发效果,确定了该方法的最优开发模式为:补充能量—闷井增能—闷井阶段—开发阶段,进一步确定了其技术界限:气水注入速度比为6.5~8.5、阶段二与阶段一增压比为0.1~0.3、注采比为0.4~0.6。将研究成果应用于胜利油田a-7区块,模拟预测表明该方法相比基础水驱开发采收率提高12.96个百分点。研究成果对复杂小断块油藏高含水期调整开发措施、提高采收率具有重要的指导意义。

Study on Oil Recovery Enhancement by Gas-Injection Stimulation Assisted by Water Flooding in Complex Reservoir with Small Fault Block

In complex reservoir with small fault block, water or gas injection is difficultly to be applied to the whole reservoir and has little effect on the further developing the remaining oil. In order to improve the recovery efficiency of remaining oil in the complex reservoir with small fault block during the high water cut stage, numerical simulation methods were employed to explore the gas-injection stimulation assisted by water flooding, and its reservoir adaptability was analyzed by economic and efficiency indicators. According to the development effect of typical models under different measures, the optimal development mode of this method was determined as follows: energy supplement-energy enhancement bu well shut-in-shut-in stage-development stage; its technical limits were further determined as follows: the ratio of gas and water injection rates was 6.5 to 8.5, the pressure ratio between Stage 2 to Stage 1 was 0.1 to 0.3, and the injection-production ratio was 0.4 to 0.6. The study results were applied to Block A-7 of Shengli Oilfield, and the simulation prediction showed that this method improved the oil recovery by 12.96 percentage points compared with basic water-flooding development. The study results play an important guiding role in the development measure adjustment and oil recovery enhancement in complex reservoir with small fault block during the high water cut stage.