A New Method of Numerical Simulation for Viscoelastic Polymer Flooding

Abstract

AbstractCurrently, polymer flooding can further improve oil recovery more than 10 percent on the basis of the water flooding in China. Many substantial indoor experiment results have shown that polymer flooding can significantly improve oil recovery because it can improve both sweep efficiency and oil displacement efficiency. Most of the current researches are from the indoor experiment by the ways of description on the rheological characteristics and the flow characterization of polymer solution in porous media. These kinds of research usually involve many parameters. However, it is very difficult to establish the polymer flooding mathematical model by the parameters from indoor experiments. So, the three mainstream percolation model describing the characterization of polymer viscoelastic flooding mechanism are reviewed respectively at first, such as synthetical resistance coefficient category, effective seepage viscosity category and residual oil reduced by normal stress category. Then taken the imperfections of current models as breakthrough, a new mathematical model with full consideration of polymer solution's viscosity and elasticity is established. After that, the corresponding numerical simulation program is completed. All the parameters in the model have clear physical meaning. Among these, characteristics of sweep volume expanded by the polymer solution's viscoelasticity are influenced by its solution properties, injection speed and reservoir pore structure; characteristics of oil displacement efficiency improved by its elasticity are considered by first normal stress difference under different shearing rate conditions. Comparing to relatively conventional mathematical models which only take polymer's viscous flooding mechanism into account, the new model can truly describe the oil displacement mechanism and production increasing effect of polymer flooding in a more comprehensive way. For the future, the establishment of the new simulation method can lay a good foundation for in-depth study on polymer flooding mechanism and its large-scale promotion and application.