低渗油田表面活性剂驱油机制

Mechanism of surfactant flooding in low-permeability oilfields

以降低启动压力理论为依据,结合表面活性剂溶液对相对渗透率影响等实验,研究表面活性剂降低油层注入压力的机制。结果表明,表面活性剂可降低油水界面张力,增加原油流动能力;表面活性剂能改变岩石表面润湿性,使岩石润湿性向亲水方向转变,减小水驱毛管阻力;表面活性剂能增加水相渗透率,降低注入压力;当表面活性剂质量分数为0.2%、注入量为0.5 VP(VP为孔隙体积)时,选择含水率低于70%注入活性剂驱油效果较好。

Based on the theories of decreasing threshold pressure and combined with experiments of the effect of surfactant solution on relative permeability, the mechanisms of decreasing pressure and increasing injection rate by surfactant were researched. The results show that the surfactant solution can reduce oil-water interracial tension, increase oil flow capacity, change wettability of rock surface from oil-wet to water-wet, decrease capillary resistance of water drive, increase water-phase permeability and decrease injection pressure. The oil displacement effect is preferable when the mass fraction of surfactant solution is 0. 2%, injection rate is 0. 5Vp（ Vp is pore volume）, and the water cut is lower than 70%.