延长低渗透油藏CO_(2)驱油参数优化数值模拟研究

Numerical simulation study on optimization of CO_(2) flooding parameters in Yanchang low permeability reservoir

CO_(2)驱油在特低渗油藏中具有较好的应用效果,是提高采收率的重要方法。以延长油田H区块为研究对象,分析目前注水开发存在的问题,根据动静态参数将井组分成2类,应用数值模拟方法,分别对2类井组CO_(2)驱油的开发方式、注气时机、注气速度、井底流压及气水交替周期进行了优化。结果表明,以气水比1∶1且气水交替的方式在油井含水40%~60%时注气效果最佳。第1类注气井组的最优注气速度为10~15 t/d,井底流压1 MPa,气水交替周期60天;第2类注气井组最优注气速度为5~10 t/d,井底流压2 MPa,气水交替周期30天。该研究结果对H区块低渗油藏现场注CO_(2)驱油设计具有重要的指导作用。

CO_(2) flooding has a good application effect in ultra-low permeability reservoirs and is a crucial method to enhance oil recovery.Taking Block H of Yanchang Oilfield as the research object,the existing water injection development problems were analyzed,and the well groups were divided into two categories according to the dynamic and static parameters.The development mode,gas injection timing,gas injection rate,bottom hole flow pressure,and water alternating gas period for the two types of CO_(2) flooding well groups were optimized by using the numerical simulation method.The results show that the best gas injection effect is achieved when the oil well water cuts are 40%~60%by gas alternating water mode with a gas water ratio of 1:1.For the first type of gas injection well group,The optimal gas injection rate is 10~15 t/d,the bottom hole flow pressure is 1 MPa,and the gas water alternating period is 60 days.For the second type of gas injection well group,the optimal gas injection rate is 5~10 t/d,the bottom hole flow pressure is 2 MPa,and the gas water alternating period is 30 days.The study results play an essential role in guiding the design of CO_(2) flooding in low permeability reservoirs in Block H.