聚合物驱后提高采收率方式实验研究

Experimental study on improving recovery factor after polymer flooding

结合孤岛油田注聚区块地层情况,优选出了适于聚合物驱后进一步提高采收率的驱油剂─—阳离子聚合物,研究了其驱油机理、在均质岩心中的驱油效果、均质岩心聚合物驱后水驱不同倍数时的驱油效果;研究了非均质地层聚合物驱后进行调剖或不调剖的驱油效果,并与具有超低界面张力的驱油剂的驱油效果进行了对比.研究表明,聚驱后注入的阳离子聚合物通过吸附、絮凝等作用可使后续水驱波及体积进一步增加,聚驱后转水驱阶段越早注入阳离子聚合物其驱油效果越好,非均质地层聚驱后对高渗层进行适当的封堵再注入阳离子聚合物可较大幅度地提高采收率.

Improving recovery factor after polymer flooding is an important problem and it takes much more attention of petroleum engineers now.A cationic polymer is selected as the oil displacement agent of the polymer flooding blocks of Gudao Oilfield.The displacement mechanism of the oil displacement agent and the displacement efficiencies under the displacement modes of “water flooding +water flooding after injecting the cationic displacement agent(or high-efficient interfacial tension displacement agent) in homogeneous core ”,“ water flooding +polymer flooding + water flooding + water flooding after injecting the cationic displacement agent(or high-efficient interfacial tension displacement agent) in homogeneous core ”,“water flooding + polymer flooding + water flooding + profile control +water flooding after injecting the cationic displacement agent(or high-efficient interfacial tension displacement agent) +water flooding in inhomogeneous core”,“ water flooding + polymer flooding + water flooding + water flooding after injecting the cationic displacement agent (or high-efficient interfacial tension displacement agent) +water flooding in inhomogeneous core” are studied by experiments,and the displacement efficiencies are compared using the cationic displacement agent with using high-efficient interfacial tension displacement agent separately.The study results show that,the cationic polymer injected after polymer flooding can increase the swept volume of the subsequent injected water by adsorption,flocculation,and so on; the earlier the cationic polymer is injected in the water flooding process after polymer flooding,the better the result of enhancing recovery factor; to inhomogeneous reservoir,the suitable shutoff of high-permeability layers can greatly enhance the recovery factor after polymer flooding; in inhomogeneous reservoir,the recovery factor enhancing value of the cationic displacement agent is greater than that of the high-efficient interfacial tension displacement agent.