不同黏弹性聚合物溶液交替注入提高采收率机理

Polymer Displacement Mechanism with Different Viscoelasticities by Alternating Injection Process

为了对比连续注入与交替注入不同黏弹性聚合物溶液对残余油滴作用力及变形的影响,从水动力学角度探索了不同性质溶液对残余油的水动力学驱替机理,分析计算了不同流体作用下残余油滴的受力及变形,从弹性及压力梯度两方面分析了交替注入不同黏弹性聚合物溶液驱油机理。在压力梯度相同的情况下驱油时,聚合物溶液作用下残余油滴所受法向偏应力和水平应力差随着聚合物弹性的增加而增加。室内物理模拟实验结果表明:与连续注入相比,交替注入不同黏弹性聚合物溶液可以改善大孔道吸液过量及小孔道吸液不足的现象,使较多的低分子量、低浓度聚合物溶液进入低渗层,表现出高渗层分流率进一步降低,低渗层分流率进一步增大,使低渗透储集层中富集的残余油有更多机会受到黏弹性聚合物的黏滞力作用而变形,从而扩大波及体积,提高驱油效率。

This paper compares the effect of continuous injection and alternating injection of polymers with different viscoelasticities onstress and deformation of residual oil droplets, explores the hydrodynamic displacement mechanism of them on residual oil, including thestress and deformation calculation of residual oil droplets under the actions of the different fluids, and analyzes the alternating injectionmechanism from two aspects of the elasticity and pressure gradient. The results show that the difference between normal deviator and hori-zontal stress of residual oil droplets by the effect of polymer solution is increasing with the elasticity rise of the polymers in the case of thesame pressure gradient. Comparing with continuous injection process, the alternating injection process of polymer solutions can improvethe phenomenon of fluid overload in the large pores and the fluid deficiency in the small pores, making the polymer of low concentrationand low molecular weight enter into the low permeability layers with more residual oil displacement and stress, hence the swept volume canbe expanded and the oil displacement efficiency can be improved.