三元体系的界面特性对驱油效率的影响机制

大量实验表明,不同碱浓度、相同界面张力的三元驱油体系的驱油效果不同。除了体系黏弹性差异之外,影响驱油效果的因素还可能与界面黏弹性有关。针对这一现象,分别使用相同界面张力、不同界面黏弹性的三元复合体系和相同界面黏弹性、不同界面张力的三元复合体系进行微观驱油实验,通过实验分析油水界面黏弹性、界面张力对驱油效率的影响机制。结果表明:三元体系的界面张力、界面黏弹性均对驱油效率有影响,降低界面张力和界面黏弹性均有利于残余油乳化及驱油效率的提高;三元体系的界面张力低、界面黏弹性低,驱油效率高;随着界面张力和界面黏弹性的降低,三元复合体系对残余油的乳化作用由乳化油滴向乳化油丝转变。上述规律与贝雷岩心实验结果一致。

Mechanism of interfacial characteristics of ASP-system on oil displacement efficiency

It is known that the effect of alkaline/surfactant/polymer (ASP) compound solution with the same interfacial tension at different alkali concentrations on residual oil is different. In addition to the difference of the ASP-solution viscoelasticity, factors affecting oil displacement efficiency could also be related to the interfacial viscoelasticity. In view of this phenomenon, the influences of ASP-system with the same interfacial viscoelastic modulus but different interfacial tension and the same interfacial tension but different interfacial viscoelastic modulus on residual oil displacement efficiency were studied using microscopic oil displacement experiment. It is indicated that the interfacial viscoelasticity and interfacial tension make contribution to the residual oil displacement efficiency. The ASP-system with low interfacial tension and low interfacial viscoelasticity has high oil displacement efficiency. Reducing interfacial viscoelasticity and interfacial tension plays an important role in enhancing oil displacement efficiency. The emulsification effect for the residual oil changes from emulsified oil droplets to emulsified oil silk along with the decrease of interfacial tension and interfacial viscoelastic modulus. The results of displacement experiment in Berea Rock Core are in agreement with the above understanding.