Displacement of a viscous oil by the combined injection of hot water and chemical additive

The modeling of an adiabatic hot waterflood assisted by the simultaneous injection of a chemical additive is presented. The process considered is one-dimensional, two-phase flow, with negligible effects of dispersion, heat conduction, and lateral heat losses. The model allows for the chemical to partition into the aqueous phase and to be adsorbed on the solid rock. The effects of temperature on the viscosity ratio and the adsorption kinetics and of chemical concentration on the fractional flow curves are included. The theory of generalized simple waves (coherence) is used to develop solutions for the temperature, concentration, and oil saturation profiles, as well as the oil recovery curves. The results obtained show that in the adiabatic case the combined injection of chemical and hot water considerably enhances the oil recovery. The sensitivity of the recovery performance to the process parameters is discussed. It is shown that, for Langmuir adsorption kinetics, the chemical resides in the heated region of the reservoir if its injection concentration is below a critical value, and in the unheated region if its concentration exceeds this critical value. Typical results for a chemical slug injection in a tertiary recovery process indicate that recovery performance is maximized when the chemicalmore » resides entirely in the heated region of the reservoir.« less