腰英台DB34井区CO_2驱替油藏数值模拟研究

为改善低渗透油藏开发效果,同时解决松南气田天然气的脱碳埋存问题,决定在腰英台油田开展CO2驱替试验.针对研究区块的地质及开发特点,建立了符合油藏地质特点的三维地质模型.应用数值模拟技术,在水驱历史拟合的基础上,设计了3种不同CO2注气方式——单段塞连续注气、周期注气、水气交替,并对注入总量、注入速度、油井流压、注气气质标准等敏感参数进行优化.结果表明,CO2最佳用量为0.8 PV,最佳注入速度为2.3×103m3/d,油井最佳流压平均为7 MPa,注入方式以水气交替注入(气水体积比1∶1)为最佳方案,预测提高采收率可达23.7%,比水驱提高14.4%.注入CO2气体中,要减少CH4的含量,添加经济适量的C2—C6组分,可提高采收率.

Numerical simulation of oil displacement with carbon dioxide in DB34 well block, Yaoyingtai Oilfield

In order to improve the development result of low permeability reservoirn DB34 well block,Yaoyingtai Oilfield,and solve the treatment of the carbon dioxide from the decarbonization of the natural gas in Songnan gasfield at the same time,it is decided to carry out oil displacement test with carbon dioxide in Yaoyingtai Oilfield.Aimed at the reservoir properties and development characteristics in study block,a 3D geological model is established based on the geological characteristics in studied area.Three gas injection modes——continuous single slug gas-injection,cyclic gas-injection and alternating injection of water and gas are designed.The gas-injection modes and the gas-injection parameters of gas-injection volume,gas-injection rate,well-bottom fluid pressure and the quality of the injected gas are optimized based on the fitting history of water flooding.The result shows that the reasonable total amount of CO2 is 0.8×106 t,optimum gas-injection rate is 23×103 m3/d,the best average well-bottom fluid pressure is 7 MPa,the better gas injection modes mode is the alternating injection of water and gas(the volume ratio of gas to water is 1∶1).Under the optimum conditions,the oil recovery factor can reach to 23.7%,it increases by 14.4% based on the recovery factor of water flooding.the recovery factor can be increased by reducing the content of methane and increasing the content of C2-C6 components in the injected gas.