A new mathematical model for polymer solution aging at reservoir conditions

Polymer aging and degradation is an important factor influencing the effect of polymer flooding in high-temperature oil reservoirs. When the effect of polymer aging and degradation on flooding effect is evaluated by means of reservoir numerical simulation,it is critical to establish the mathematical model for polymer aging and degradation. The viscosity correction model at reservoir conditions was built by using the first-order ordinary differential equation of polymer aging and degradation. Then, the partial differential equation for describing the variation of polymer viscosity at reservoir conditions was presented. Combined with the mass conservation equation of polymer, it is proved that the viscosity correction model is feasible if the viscosity-concentration relation is polynomial.The viscosity correction model reveals the influential process of degradation and flowing of polymer on its viscosity at any point of oil reservoir, and describes the physical phenomenon of viscosity reduction with constant mass concentration in the process of polymer aging and degradation. Compared with the viscosity models used in current commercial numerical simulators, this model can present the physical flowing of polymer in porous media more actually. The derivation and demonstration of viscosity correction model provides the theoretical support for the numerical simulation study of polymer aging and degradation.