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低渗透油藏储层致密,水驱后期,含水率逐渐增高,驱替效率也随之降低,剩余油潜力依然较大。应用CO_2驱油技术,一方面可以较大幅度的提高采收率,同时也可将一部分的CO_2封存在地下。通过室内CO_2、水交替驱油实验以及实际生产,分析了采收率提高情况以及影响采收率提高的因素。结果表明:气水交替驱最终驱油效率51.2%~62.7%,平均58.7%,比水驱油平均高10.1%;尤其以渗透率大于1.0×10~(-3)μm~2的样品采收率提高比较显著;气水交替驱,不同渗透率岩样在注入0.5 PV的气体或者水时躯替效率提高最大;驱替压差与渗透率呈反比关系,随着驱替压差的减小驱油效率增大;低渗透油藏在实际注气生产过程中,应综合考量各类因素的影响,制定合理的注采方案。
The reservoirs of low permeability reservoirs are dense, and the water cut gradually increases in the late stage of water flooding, and the displacement efficiency also decreases. The residual oil potential remains high. The application of CO_2 flooding technology, on the one hand, can greatly enhance the recovery rate, but also can be part of the CO 2 sealed underground. Through the experiment of indoor CO_2 and water displacing oil displacement experiment and actual production, the factors that affect the oil recovery and the recovery rate are analyzed. The results show that the final displacement efficiency is 51.2% ~ 62.7% with an average of 58.7%, which is 10.1% higher than that of water flooding, especially with samples with permeability higher than 1.0 × 10 ~ (-3) μm ~ 2 The rate of increase is more significant. When gas and water are alternately driven, the displacement efficiency of rock samples with different permeability increases most when the gas or water of 0.5 PV is injected. The displacing pressure and permeability are inversely proportional to each other. With the decrease of displacement pressure Oil displacement efficiency increases; low permeability reservoirs in the actual injection process, should consider the impact of various factors, develop a reasonable injection program.