The Numerical Computation Of Viscoelastic Fluid In The Micro-pore

Polymer flooding was a new technique which was applied in the oil-field during three-recovery, the visual experiment proved: it can improve oil recovery largest. The residual oil film distributed in different forms with its cohesion,adhesion of rock to the residual oil,interface free energy between oil film and driving fluid. Polymer solution has high viscoelasticity, with pulling of polymer solution and interfacial tension together, in the upstream of the residual oil film, it decreased thin and scaled off gradually, in the downstream of the residual oil film, it formed discrete oil droplets, which were carried by the polymer solution, and then the residual oil film accumulated gradually, repeated the process. Adopting common conversion Oldroyd-Maxwell constructive equation, in this paper, the flow equation of viscoelastic fluid in the micro-pore was established, and was calculated with the Polyflow (Computational Fluid Dynamic software),and was given boundary condition; the velocity and stress profile were obtained; the relaxation time, oil film size, flow channel width that have influence on the velocity and stress profile were analyzed; the normal stress and tangential stress which acting on the residual oil film were calculated. The result shows that the normal stress and tangential stress which acting on the residual oil film relate to viscoelasticity of driving fluid; the bigger the elasticity of the driving fluid is , the smaller the extreme of velocity is, the bigger the normal stress and tangential stress which acting on the residual oil film are; the stress of polymer flooding is bigger than that of water flooding; the upstream of the residual oil film is pressed, the downstream of the residual oil film is pulled, the result is that the advancing contact angle changes bigger, the receding contact angle changes smaller, which causes more deformation, hence it is favor of startup of the residual oil.