Yan Yiqun, Wang Lihui, Sang Guoqiang, Han Xu
Research Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083, China.
Postdoctoral Research Workstation of Daqing Oilfield, Daqing 163458, China.
Polymers (Basel). 2022 Feb 26;14(5):940. doi: 10.3390/polym14050940.
To investigate the impact of polymer viscoelasticity on microscopic remaining oil production, this study used microscopic oil displacement visualisation technology, numerical simulations in PolyFlow software, and core seepage experiments to study the viscoelasticity of polymers and their elastic effects in porous media. We analysed the forces affecting the microscopic remaining oil in different directions, and the influence of polymer viscoelasticity on the displacement efficiency of microscopic remaining oil. The results demonstrated that the greater the viscosity of the polymer, the greater the deformation and the higher the elasticity proportion. In addition, during the creep recovery experiment at low speed, the polymer solution was mainly viscous, while at high speed it was mainly elastic. When the polymer viscosity reached 125 mPa·s, the core effective permeability reached 100 × 10 μm, and the equivalent shear rate exceeded 1000 s, the polymer exhibited an elastic effect in the porous medium and the viscosity curve displayed an 'upward' phenomenon. Moreover, the difference in the normal deviatoric stress and horizontal stress acting on the microscopic remaining oil increased exponentially as the viscosity of the polymer increased. The greater the viscosity of the polymer, the greater the remaining oil deformation. During the microscopic visualisation flooding experiment, the viscosity of the polymer, the scope of the mainstream line, and the recovery factor all increased. The scope of spread in the shunt line area significantly increased, but the recovery factor was significantly lower than that in the mainstream line. The amount of remaining oil in the unaffected microscopic area also decreased.
为研究聚合物粘弹性对微观剩余油开采的影响，本研究采用微观驱油可视化技术、PolyFlow软件中的数值模拟以及岩心渗流实验，来研究聚合物的粘弹性及其在多孔介质中的弹性效应。我们分析了不同方向上影响微观剩余油的力，以及聚合物粘弹性对微观剩余油驱替效率的影响。结果表明，聚合物的粘度越大，其变形越大，弹性比例越高。此外，在低速蠕变恢复实验中，聚合物溶液主要表现为粘性，而在高速时主要表现为弹性。当聚合物粘度达到125 mPa·s、岩心有效渗透率达到100×10μm且等效剪切速率超过1000 s时，聚合物在多孔介质中表现出弹性效应，粘度曲线呈现“上升”现象。而且，作用于微观剩余油的法向偏应力和水平应力的差值随着聚合物粘度的增加呈指数增长。聚合物粘度越大，剩余油变形越大。在微观可视化驱替实验中，聚合物的粘度、主流线范围和采收率均增加。分流线区域的波及范围显著增加，但采收率明显低于主流线区域。未受影响的微观区域内的剩余油量也减少。
