致密油藏微乳液降压增注机理研究及性能评价

Study on mechanism and performance evaluation of microemulsion depressurization and augmented injection in tight oil reservoirs

针对微裂缝型低渗透致密油藏存在的高压欠注的问题,开发出一种微乳液型的降压增注体系,体系配方为:OP系列乳化剂+聚醚表面活性剂+油相+NaCl溶液。评价了微乳液体系的配伍性能、增溶性能、抗温性能以及界面张力,结果显示:微乳液能够降低油水界面张力,改善岩石的润湿性,提高波及面积和洗油效率,对高矿化度地层水有良好的配伍性,抗温达到70℃,界面张力达到10^-2数量级。岩心驱替试验表明:微乳液对降低低渗透岩心的注水压力有明显作用,注入1PV质量分数为10%的微乳液能将注水压力降低41.27%。

A microemulsion type depressunzation and augmented injection system is developed for the problem of high pressure underfill in micro-fracture low permeability tight reservoirs.The formulation of the system is: OP series emulsifier + polyether surfactant + oil phase + NaCl solution.The compatibility, solubilization, temperature resistance and interfacial tension of the microemulsion system are evaluated.The results show that the microemulsion can reduce oil-water interfacial tension, improve rock wettability, increase swept area and oil washing efficiency, and has good compatibility with high salinity formation water. Its temperature resistance can reach 70 ℃, and the interfacial tension can reach 10 ^-2 .The indoor core flooding experiment shows that the system has obvious effect on reducing water injection pressure of low permeability core. Injection 1 PV 10%( w ) microemulsion can reduce water injection pressure by 41.27%.