聚驱后聚表二元复合体系提高残余油采收率研究

Study on enhancing the recovery factor of residual oil by polymer/surfactant compound system after polymer flooding

利用不加碱可形成超低界面张力的聚丙烯酰胺/甜菜碱表面活性剂二元复合体系,通过流变性实验,分析了活性剂质量浓度对聚表二元复合体系黏弹性的影响;通过在仿真岩心模型上的驱油实验,分析了不同黏弹性的聚表二元复合体系对聚驱后采收率的影响.研究表明:实验用的两性表面活性剂体系对无碱二元体系的黏弹性影响很小,二元驱油体系的黏弹性越大,聚驱后二元驱的采收率增加幅度也越大.在注入压力允许的条件下,界面张力不一定要达到超低,适当增加聚合物溶液的黏弹性,也可以达到超低界面张力时的驱油效果.

After polymer flooding,there is still about 50% of residual oil.In order to further enhance oil recovery factor,it is put forward that after polymer flooding,an amphoteric surfactant/polymer compound solution (for short SP solution) is used for the displacement of the residual oil,this compound oil displacement system can gain ultra-low interfacial tension without alkali.The effect of the mass concentration of the amphoteric surfactant on the rheology characteristic of the SP solution is analyzed through rheological experiments;the effect of the amphoteric surfactant/polymer compound solution with different viscoelasticity on the recovery factor of the residual oil after polymer flooding are studied by the oil-displacement experiments of visible etched glass core.It is shown that the amphoteric surfactant has a little influence on the viscoelasticity of the SP solution without alkali;the greater the viscoelasticity of the polymer/amphoteric surfactant compound system,the greater the increment of the recovery factor increased by the SP compound flooding.Within the limit of injection pressure,the recovery factor under the condition of ultralow interface tension can be obtained by increaseing the viscoelasticity of SP solution under non-ultralow interface tension.