Research On Oil Displacement Efficiency Of Viscoelastic Polymer Solution Flooding Based On Three-dimensional Network Model

The polymer solution flooding has become the most commonly used method of enhanced oil recovery in the domestic tertiary oil recovery technology. In oil recovery process using a polymer solution, polymer solution in porous media flow characteristics directly affects the polymer flooding oil recovery. However, the polymer solution flow in porous media is extremely complex, it depends not only on the nature of the polymer solution, and also vary depending on the micro structural parameters of the porous media. So further determine the pore structure parameters and injection parameters and polymer solution viscoelasticity to improve the oil displacement efficiency of polymer flooding has important value.The paper was on the base of porosity parameters which is obtained by the pressing mercury experiment of the artificial core, considering the coordination number, pore-throat ratio, shape factor and the wettability of model, more accurately simulate the real structure of the reservoir characteristics. Similar principles of hydropower combined with flow conservation law, consider the viscoelastic of polymer solution, relative molecular mass, mass concentration and interfacial tension, achieve a multiphase fluid flow in porous media.Then in accordance with the actual development of the real reservoir, the process of oil saturated, first water flooding and polymer flooding are simulated. In the simulation of polymer solution flooding process, by changing the pore structure parameters and injection parameters in order to study the impact of these parameters on the recovery of polymer flooding, also give special consideration to the polymer solution through the porous medium to produce additional pressure recovery polymer flooding. The results showed that:with the pore throat radius increase, in the wet system, oil displacement efficiency of polymer flooding gradually reduced, in the oil-wet system, oil displacement efficiency of polymer flooding gradually increased; with the coordination number increase, fluid seepage channel increased, the oil displacement efficiency of polymer flooding enhanced; with the pore-throat ratio increase, the oil displacement efficiency of polymer flooding reduced; with the shape factor increase, throat cross-sectional shape more rules and corner reduce, the oil displacement efficiency of polymer flooding enhanced; with the relative molecular mass and mass concentration of polymer solution increase, the oil displacement efficiency of polymer flooding enhanced; Reduce the interfacial tension of the polymer solution system also can be further improved the oil displacement efficiency of polymer flooding; considering the elasticity when the polymer solution through the porous medium can improved the oil displacement efficiency of polymer flooding.