Mathematical Model and Numerical Simulation Development of Viscoelasticity Polymer Flooding in Heavy Oil Reservoir

Polymer flooding is widely used in the development of offshore heavy oil fields for higher recovery. Apart from main functions such as increasing water viscosity, the viscoelastic properties of polymer which would lead to reduced residual oil saturation has been found in experiment and field studies. Additionally, the heavy oil flow exhibits threshold pressure gradient (TPG) due to its high viscosity. In this paper, a novel mathematical model incorporating the polymer viscoelasticity, diffusion and TPG effect of heavy oil is established. The NDE number proposed by Qi et al. 2017 is adopted to describe the residual oil saturation variation with viscoelasticity. Simulator is implemented with FORTRAN language and validated with the commercial software. Systematic analysis shows that the polymer viscoelasticity decreased the water cut rising and enhances the development performance. A reduction of residual oil saturation was observed in the near injection well with high flow velocity and polymer concentration. With the consideration of TPG in heavy oil, the oil enhancement by polymer flooding becomes more obvious. The effect of polymer flooding and polymer viscoelasticity both decreases with polymer diffusion. Good history matching of the S oilfield indicates that the applicable of this model. This new model facilitates more accurate simulation of polymer flooding in the heavy oil reservoirs.