超低界面张力的二元驱油体系对水驱残余油启动和运移机理

针对三元复合驱含碱驱油体系引起地层黏土分散和运移、形成碱垢、导致地层渗透率下降,碱还会大幅度降低聚合物溶液的黏弹性,从而降低波及效率等问题,利用新研制的不加碱可形成超低界面张力两性表面活性剂,通过微观模型驱油实验,分析了聚丙烯酰胺/两性表面活性剂二元复合体系对残余油启动、运移的过程,研究了该二元复合体系对水驱后残余油的作用机理.研究表明:具有超低界面张力的聚表二元复合体系利用了聚合物溶液的黏弹特性和表面活性剂体系的超低界面张力特性,使采收率大幅度提高.残余油的启动主要以拉成油滴和油丝两种形式,在运移过程中,较大的油滴又形成更容易被驱替液携带的小油滴,从而使驱油效率提高.

Start-up and migration effect of the polymer/Surfactant solution with ultralow interfacial tension on the residual oil after water flooding

Three-component oil-displacement system containing alkali will cause the dispersion and migration of formation clay and the formation of alkali scale,and it will also cause the decrease of formation permeability.The alkali in the system will also greatly reduce the viscoelasticity of the ASP solution and therefore reduce the sweeping efficiency of the three-component oil displacement.For solving these problems,a new alkali-free amphoteric surfactant with ultra-low interfacial tension is studied.The starting-up and migrating process and mechanism of polyacrylamide /amphoteric oil-displacement system to the residual oil after water flooding ASP flooding are studied by micro-model oil-displacement experiment.It is shown that the polymer/surfactant oil-displacement system makes uses of the viscoelasticity of the polymer solution and the ultra-low interfacial tension of the surfactant system to greatly enhance recovery factor.The start-up of the system to the residual oil is mainly in the forms of drawing it into oil-drop and oil-thread.In the migration process of the oil drop,the bigger drop is drawn into smaller oil-drop which can be carried easier by SP compound solution,so the oil displacement efficiency can be enhanced.