The Effects of Temperature-Dependent Fluids' Viscosity on the Performance of a Polymer Flood in Reservoir Systems with an Elevated Temperature

Abstract

Accurate assessment of the potential of a nonisothermal polymer flood process requires a model on the viscosities of reservoir fluids as a function of temperature. A three-dimensional numerical model for fluid flow, mass transport, and energy balance is used to analyze the performance of the reservoir in a five-spot pattern operating under polymer flood followed by waterflood. The nonisothermal scheme can be used as a quantitative tool to evaluate the comparative studies of different polymer flooding scenarios with respect to temperature dependence of fluids' viscosities. Results of cumulative recovery and water-oil ratio at the production well are presented for various types of temperature dependencies, reservoir temperatures, and oil viscosities. Significant improvement in predicted oil recovery and reduction in water-oil ratio is obtained for the case of including temperature dependencies of both water and oil because the reduction of oil viscosity is larger than that of brine viscosity. The inclusion of heat loss to over/underburden formations had little effect on the oil recovery because of the relatively small temperature difference under the conditions considered in this study. More rapid reduction of oil viscosity results in the considerable reduction in mobility ratio and significant increase of oil recovery at a higher temperature.