In the late stage of high water cut in sandstone oilfield,the dominant flow field is seriously developed,which restricts the further improvement of water drive recovery.In this paper,AHP and fuzzy comprehensive evaluation combined with numerical simulation method are used to determine the weight of the influencing factors of the dominant flow field in the reservoir plane.The fuzzy comprehensive evaluation index (FCI) of the advantaged flow channel is obtained by fuzzy calculation of the constructed matrix,and the production and injection well with the advantaged flow channel is determined by the FCI value. Basing on the study of the advantaged flow channel,water injection volume of ineffective circulating injection wells is reduced and injection layer is adjusted to enlarge the water⁃flooding area and to achieve the aim of further tapping the remaining oil with the idea of fine injection and production adjustment.This method is adopted to determine the advantaged flow channel of a block of V Oilfield.Among them,seven production and injection well pairs exist in advantaged flow channel area,five production and injection well pairs exist in much more advantaged flow channel areas.The comprehensive water cut in V Oilfield is reduced by 1.1%,the cumulative crude oil yield rises up to 2.2×104 t,achieving a good effect for taping reminding oil and controlling water cut by the deep profile and periodic water injection in injection well with the production well shutting off adjustment for 12 well groups which is in advantaged flow channel areas.

A simulation experiment is carried out for polymers which are different from the viscoelasticity of Newtonian fluids. In order to describe the rheology of polymer solution accurately, the constitutive equation of Maxwell is used to control the fluid characteristics. What's more, a physical model of polymer solution flowing in the micro waterwet capillary is established. Finally, CFD software was used to carry out numerical analysis of the model. The pressure fields, stress fields and velocity fields of polymer flow are obtained by numerical simulation, and the change state of polymer flooding is studied. Through pressure, stress, velocity field changes, we can intuitively realize that in the process of polymer flooding, the unique elasticity of the viscoelastic fluid increases the volume of the residual oil by the displacement fluid during the extrusion collision, and makes the original flow of oil flow. The research results can further improve the polymer flooding microscopic seepage theory.