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特高含水期后期,地层剩余油主要以油膜、盲端残余油等形态存在,水驱开发效果变差,采用黏弹性流体驱替是当前提高采收率的有效方法.为探索黏弹性流体驱替残余油的水动力学机理,基于N-S方程模拟黏弹性流体在微孔道内流动.采用Oldroyd-B本构方程描述流体的黏弹性,运用相场方法实时追踪驱替过程中两相界面.分别研究壁面油膜在黏弹性流体驱替下的运动和变形,黏弹性流体对盲端残余油的驱替效果,并分析残余油微观受力状况.采用有限元方法对模型进行求解,并验证模型与求解的正确性.研究结果表明:黏弹性流体可以有效驱动壁面油膜运动,相同注入流量下,黏弹性流体作用于壁面油膜上的水平应力差远大于水;作用于油膜上的法向应力分布不均匀导致油膜发生较大变形.同时黏弹性流体在盲端内的波及边界更深,有利于引发盲端残余油的运动,提高残余油采收率.黏弹性流体驱替对水湿油藏开发增产效果更明显.该研究初步揭示了黏弹性流体驱替残余油的水动力机理,为油田三次采油提供有效指导.
In the late period of the ultra-high water-cut period, residual oil in the strata exists mainly in the form of oil film and residual oil at the blind end, and the development effect of water flooding is deteriorated. The use of viscoelastic fluid displacing is an effective method to enhance oil recovery. Based on the Navier-Stokes equations, the viscoelastic fluid flows in the microchannels are simulated based on the Navier-Stokes equations. The Oldroyd-B constitutive equation is used to describe the viscoelasticity of the fluid and the phase field method is used to track the two-phase interface in the displacement process in real time The displacement and deformation of the wall oil film under the viscoelastic fluid displacement and the displacements of viscoelastic fluid to the residual oil at the blind end were studied and the microscopic forces on the residual oil were analyzed.The finite element method was used to solve the model and verified that the model and The results show that the viscoelastic fluid can effectively drive the movement of the wall oil film and the horizontal stress difference of the viscoelastic fluid acting on the wall oil film is much larger than that of the water under the same injection flow rate.The normal stress distribution on the oil film is not good Uniform deformation of the oil film occurs.Meanwhile viscoelastic fluid in the blind end of the wave boundary and deeper, is conducive to triggering the blind end of the residual oil movement, improve residual oil recovery Rate. Viscoelastic fluid displacement more pronounced effect on the water-wet reservoir development stimulation. The preliminary study revealed the hydrodynamic mechanism of residual oil viscoelastic fluid displacement, to provide effective guidance for the EOR oil.