The Research Of Relative Permeability And Oil Displacement Efficiency Of Polymer Flooding Based On Three-dimensional Network Model

The efficiency of polymer flooding is influenced by the pore structure characteristics, wettability and other factors. Therefore, a comprehensive study of the flow of polymer solution in the complex porous medium, analysis of the influence of pore connectivity, pore size, pore geometry, pore-throat ratio and other basic pore structure characteristics on the relative permeability curve and displacement efficiency of polymer flooding, analysis of the relationship between relative permeability curve and the displacement efficiency, this have important guiding significance for the theory on how to further improve the recovery efficiency.In this paper, the micro-structure of complex pore throat of the reservoir medium are described though regular geometry images, interconnected channels and nodes, and the three-dimensional network model is built. The probability of different sizes pore throat is assumed by using Haring-Greenkorn distribution function. The shape factor, porosity and diversion efficiency etc. parameters are calculated, which provides basic data for the simulation process. Application of constructing the network model, in terms of the distribution status of the fluid in pores, the process of saturated oil, water displacing oil and polymer flooding are simulated by the way of piston-like displacement, block displacement and porefilling displacement, the effect of pore structure features on relative permeability curve of polymer flooding is analyzed. The result indicates that, increasing coordination number, enlarging the shape factor, increasing throat radius, decreasing the throat to pore ratio and enlarging the average radius of the throat can be favorable to increase the oil permeability and enhance oil displacement efficiency. In the paper, the water distribution of network model profiles is given and the oil and water distribution after water flooding and polymer flooding in the model is described. The application of simulation examples of network model compared with the experimental data, are almost identical, which is proved the veracity of network model of simulating the relative permeability curve.