特高含水期微乳液驱油规律微观可视化实验研究

Microscopic Visualization Study of Microemulsion Flooding Law in Ultra-high Water Cut Stage

为深入探究特高含水期微乳液提高采收率的规律,设计了微观可视化驱替装置,在分析水驱剩余油的宏、微观分布特征基础上,对特高含水期微乳液驱进行了实验研究。实验结果表明,在特高含水期,中相微乳液的增溶作用对膜状剩余油的动用最为明显;微乳液能将剩余油乳化拉丝,油丝断裂形成乳状油滴,小油滴易于流动,体积较大的乳化油可聚并下游剩余油,富集形成油带被驱替出;微乳液中表面活性剂可将油水界面张力降至10-3 mN/m量级,超低界面张力有利于驱替相突入连片状剩余油中,实现对剩余油的分割动用,有效提高特高含水期剩余油的采出程度。

To further study the recovery factor enhancing law of microemulsion flooding in ultra-high water cut stage,a visual displacement device was designed.On the basis of the analysis of the macro and micro characteristics of residual oil distribution after water flooding,the behavior of microemulsion flooding in ultra-high water cut stage was studied by visual experiments.The experimental results show that the solubilization of middle phase microemulsion is most obvious for the flooding of membrane residual oil.Microemulsion could emulsify the residual oil into oil wires,and the oil wires break and form emulsified oil droplets.Small oil droplets were easy to flow in porous media,and larger emulsified oil droplets could gather with the residual oil downstream and enrich to form oil belts which could be displaced later.The surfactant in the microemulsion reduced oil-water interfacial tension to the order of 10-3 mN/m.The ultra-low interfacial tension was conducive to the penetration of displacement phase into crude oil,so as to realize the segmentation and activation of continuous residual oil.Thus,the oil recovery factor in the ultra-high water-cut stage could be enhanced effectively.