黏弹性聚合物驱渗流机理研究进展

FLOW MECHANISM OF VISCOELASTIC POLYMER FLOODING:STATE OF THE ART REVIEW AND OUTLOOK

聚合物驱已成为国内外化学驱中提高原油采收率主要方法之一,其在大庆油田的60年开发稳产中起到重要作用,在水驱基础上提高原油采收率达到约13%.聚合物驱主要机理为改善流度比,提高注入液的波及体积,从而提高驱油效率.近几年,聚合物溶液黏弹性能够进一步扩大其在多孔介质中的微观波及面积从而提高微观驱油效率的作用机理也逐渐被人们所认识.文章从聚合物溶液黏弹特性、聚合物驱微观可视化实验、岩心驱替实验及驱油机理理论研究4个方面进行了综合分析,对比论述了国内外关于黏弹性聚合物溶液渗流机理的研究现状、实验手段及方法,给出了聚合物溶液的黏弹性产生的法向应力能够进一步对水驱后残余油产生“拉”“拽”作用,从而使其比纯黏性流体进一步提高在多孔介质内的微观波及效率及驱油效率,明确了弹性湍流是产生表观增稠的本质,对提高驱油效率产生一定的正向影响.最后针对黏弹性聚合物驱渗流机理研究面临的问题及发展方向进行总结,弹性湍流产生的条件、黏弹性对不同尺寸孔隙内不同类型原油采收率的贡献及弹性与油藏润湿性的协同影响等机理成为未来研究的挑战与方向.论文的归纳能够为黏弹性聚合物溶液机理深入研究及矿场设计优选聚合物提供重要的参考.

Polymer flooding is the most important method used to improve the oil recovery in the oilfield,it plays an important role in the 60 years Daqing Oilfield development,the oil recovery was enhanced to 13%more than that of water flooding.The main mechanism of polymer flooding is improving the flow mobility between water and oil,and increase the sweep volume,thus the oil recovery can be enhanced.In recent years,the mechanism that the viscoelasticity of polymer solutions can increase the micro sweep area in porous media and thus enhance the micro oil displacement efficiency has also been gradually investigated.Therefore,in this study,the characteristics,micro flooding experiments,core flooding experiments and the theoretical study of viscoelastic polymer are reviewed,and the current research status,experimental methods and approaches on the flow mechanism of viscoelastic polymer solutions are discussed.Then,it is shown that the normal stress generated by the viscoelasticity of the polymer solution can further pull and tug on the residual oil after water flooding,and promote deformation of residual oil,which can further improve the micro sweep efficiency and oil displacement efficiency in porous media than that of pure viscous fluids.The essence of elastic turbulence to cause apparent thickening is clarified,which has a certain positive impact on the improvement of oil displacement efficiency.Finally,the problems and development directions of the mechanism of viscoelastic polymer flooding are summarized,and the conditions of elastic turbulence,the contribution of viscoelasticity to the recovery of different types of crude oils in different sizes of pores,and the synergistic effect of elasticity and wettability have become the challenges and directions for future research.The paper can provide an important reference for the mechanism study of viscoelastic polymer solution and the selection of optimal polymer solution in the oilfield.