Flow Of Viscoelastic Polymer In Undulating Tube And Its Effect On Residual Oil

In this thesis,a great deal of work is reviewed including the status quo of improved oil recovery theories on polymer flooding ,model of porous media, model for viscoelastic fluid .it is shown that the basic theories on polymer flooding is far from complete ,research on the mechanism of microscopic displacement commonly bases on laboratory studies ,the theoretical research needs further on .so that ,besides choosing proper model for viscoelastic fluid and geometric model characterizing reservoir pores, effective numerical methods should be used to solve mathematical model ,so as to theoretically study the effect of viscoelastic polymer fluid on oil . 1. Reservoir pore model and model of viscoelastic fluidBased on the types of residual oil in pore media after water flooding and contraction-expansion characteristic of inner channel in actual pore media , select undulating tube model which has the contraction-expansion cyclical process and the simple geometry ; based on the viscoelasticity of polymer fluid in reservoir pore ,select upper-convected Maxwell model which is generally applied to numerical calculation of viscoelastic fluid flowing in complex channels. In order to study thereotically the displacement mechanism of viscoelastic fluid, we study the problems with porous dimension. Result of numerical calculation shows that viscoelastic effect of polymer fluid in pore media can be showed in the undulating tube model.2. flow characteristic of polymer fluid in undulating tubewe construct the mathematics model made up of continuity equation, equation of motion, UCM constitutive equation, stream function, vorticity equation as well as the boundary conditions, by constructing the algebra grid in cylindrical coordinate system and the elliptic grid in orthogonal curvilinear coordinate system and adopting finite difference method for numerical calculation, we calculate stream function field, velocity field and stress field in reservoir condition, comparing the result with one in literature and comparing the result between this two methods, we find both results are same on the whole ,which testifies our numerical method is success.3. flow characteristic of two-phase of polymer fluid and oil filmstudy flow characteristic of two-phase of polymer fluid and oil film in equal diameter circular tube.for the interface of residual oil in the wall and polymer fluid is ripple shape, it belong to the field of studying flow in undulating tube. The same numerical model and the elliptic grid in orthogonal curvilinear coordinate system as above is used in the numerical calculation, which is not repeated. Ultimately ,we calculate the flow characteristic of viscoelastic polymer fluid : first normal stress enlarge with the enlargement of We, shear stress vary little with the enlargement of We, when a is larger, stream line in contours of stream function obvious upward compared with it in Newtonian fluid and swept volume enlarged with the enlargement of We.4. the effect of viscoelastic polymer fluid on residual oil filmin this paper ,the mechanism .of improve oil displacement efficiency of polymer fluid with theories analysis is: (1)because the rolling action on oil film by first normal stress and shear stress from viscoelastic polymer fluid is larger than one by shear stress from Newtonian fluid with same viscosity, residual oil film can flow partly, (2)comparing polymer fluid with Newtonian fluid ,the same stream line is not in the same position, and the swept volume of viscoelastic polymer fluid is larger than Newtonian fluid with same viscosity.