用亲水露头砂制备水测渗透率分别为0.030、0.197、0.508μm^2的3组人造柱状岩心,每组岩心分为表面亲水(不处理)、中性润湿(经甲基硅油处理)、亲油(经胜利原油煤油混合油处理)3类,其表面润湿性经切片测定动态接触角确认。分别用矿化度19.4g/L的模拟胜利地层水和模拟油测定岩心渗透率。相同渗透率岩心的水测渗透率,岩心表面亲水时最高,中性润湿时次之,亲油时最低,变化幅度随渗透率的增大而减小,最大达600倍;油测渗透率则在表面中性润湿时为最高,亲油时次之,亲水时最低。岩心的水驱采收率,以岩心表面中性润湿时为最高,表面亲水时大幅下降,表面亲油时最低,但与表面亲水时相比,降幅不大。认为油润湿是低渗透油藏注水压力高的原因之一,将油藏润湿性转为中性,可提高水(及化学驱油剂)的注入能力。表3参8。
Lots of artificial cores of water permeability, Kw, 0.030, 0. 197, and 0. 508 μm^2 are prepared from an outcrop sand and are treated partly with a methyl silicone oil and partly with a crude/kerosene mixture to make their surface neutrally wetting or oil wetting with the remained cores keeping water wetting surfaces. The surface wettability of cores is ascertained by determining dynamic contact angles on cut sections. The permeability of the cores is measured to a flooding water of TSD = 19.4 g/L and a simulation oil. The water phase permeability is arranged in a decreasing order: water wetting〉neutrally wetting〉oil wetting at equal Kw value and the changes in permeability increases with increasing Kw value, giving a largest value of 600 times. The oil phase permeability of cores at equal Kw value is arranged in a decreasing order: neutrally wetting〉oil wetting〉water wetting. The highest oil recovery by waterflcod is observed in neutrally wetting cores, a significant decrease in oil recovery-in water wetting cores and the lowest, a little droped, oil recovery-in oil wetting cores. It is considered that oil wettabflity of rock surfaces is one of the important rea- sons for raised water injection pressure at low permeability sandstone oil reservoirs and conversion of reservoir rock wettability to neu- trally wetting is a way of enbacing injectivity of water (and chemical flooding fluids).