The Research On The Mechanism Of Oil Displacement Efficiency By Polymer Flooding With Viscoelasticity

In this thesis, a great deal of work is reviewed including the status of the mechanism of polymer flooding enhanced oil recovery, model of porous media and model of viscoelasticity liquid. It is shown that the basic theories on polymer flooding was faultiness, and the mechanism of viscoelasticity polymer enhanced the oil recovery still rely on laboratory research, and the theoretical research needs further on. In the paper, based on the analysis of experiment, through the selection of model of viscoelasticity liquid, the simplification of model of porous media, and effective numerical methods should be used to solve mathematical model, the viscoelastic polymer flooding mechanism is studied on the theories.In this paper, the experimental study of the viscoelastic properties of polymer solution was done, through Static and dynamic data using a combination of approaches, a wide range expression of polymer rheological parameters is established and a wide range of shear rate for the first normal stress difference of values is received. Used algebraic grid in the cylindrical coordinates and the elliptic mesh method under general orthogonal curvilinear coordinates, numerical Solution is received by using finite difference method. The stream function field, the velocity field, stress field of polymer solution in the simplified undulating tube flow under the Reservoir conditions has been attained. The effect of polymer viscoelastic properties on the stream function field, the velocity field, stress field and its mechanism of the film is studied. To nuclear magnetic resonance, Fluorescence analysis of the core piece wear test and visualization experiments as a means of flooding reveals the mechanism of viscoelastic polymer solution to enhanced oil recovery. On the basis of the physical simulated results, the distribution and changement of remaining oil after polymer flooding is received by using nuclear magnetic resonance and the core piece wear fluorescent analysis, determined the existence of different types of micro-residual oil in the water flooding and determined the distribution law of macro- remaining oil afterpolymer flooding. Through the micro-visual flooding experiments, the effect mechanism of viscoelastic polymer solution on residual oil of in different wettability the dead-end model is studied, the effect of displacement speed changement on residual oil both oil wet and water wet oil and the effect of polymer viscoelastic properties on residual oil film is analyzed. The displacement efficiency of the viscoelastic polymer solution with different characteristics at the simulation core is studied, and the research further revealed the displacement mechanism of viscoelastic fluid on residual oil after water flooding from the microscopic point of view, perfected microscopic seepage theory of polymer flooding, thus the viscoelastic polymer solution displacement of residual oil potential capacity is made full and accurate scientific evaluation.