水驱后三元复合驱全过程的相渗曲线变化趋势研究

选用大庆油田有代表性某储层天然岩心的平行样,水测渗透率分别在1 000、600、200×10-3μm2左右。采用恒速非稳态法分别测定了水驱、三元复合驱(注入0.8 PV)及后续水驱全过程的相对渗透率曲线。研究结果表明:注入三元复合体系溶液后相渗曲线形态发生明显变化:驱替相的相对渗透率先降后升,油相的相对渗透率先升后降;且相渗曲线的等渗点增加(本实验增加为3个);岩心渗透率越高,第一等渗点与第三等渗点的跨度越大,残余油饱和度越低。

The Research on Relative Permeability Curves of the Full Term of Alkali-surfactant-polymer Flooding after Water Flooding

In this paper, three kinds of representative parallel natural core samples are selected from someone reservoir in Daqing Oilfield, which water permeability are about 200, 600,1000 millidarcy, and the unsteady-state method of constant injection rate is adopted to measure the relative permeability curves of the whole process of water flooding up to water-cut 98%, then alkali-surfactant-polymer(ASP) flooding(0.8 pore volume), sequent water flooding. The results show that, the displacing phase relative permeability declines at first, then ascends after injecting ASP solution, but the oil relative permeability is just opposite; except the first one, there are another two points at which the displacing phase relative permeability is equal to the oil relative permeability; for the same displacement process, the span between the first point and the third point at which the displacing phase relative permeability is equal to the oil relative permeability is variational, the higher the natural core permeability is, the larger the span is and the lower the residual oil saturation is.