Displacement of a Viscous Oil by the Combined Injection of Hot Water and Chemical Additive

Summary A model of an adiabatic hot waterflood assisted by the simultaneous injection of a chemical additive is presented. The process considered is one-dimensional (1D), two-phase flow, with negligible effects of dispersion, heat conduction, and lateral heat losses. The model allows for the chemical to be soluble in the aqueous phase and to be adsorbed on the solid surface. The effects of temperature on the viscosity ratio and the adsorption thermodynamics and of chemical concentration on the fractional flow curves are considered. The theory of generalized simple waves (coherence) is used to develop solutions for the temperature, concentration, oil-saturation profiles, and oil-recovery curves. The results show that, in the adiabatic case, the combined injection of chemical and hot water enhances the oil recovery considerably. The sensitivity of the recovery performance to the process parameters is discussed. It is shown that, for Langmuir adsorption equilibrium, 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 pulse injection in a tertiary recovery process indicate that the recovery performance is maximized when the chemical resides entirely in the heated region of the reservoir.