HYDROCARBON RECOVERY WITH INJECTED SOLVENT AND STEAM AT SELECTED RATIOS

A method of recovering hydrocarbons from a subterranean reservoir comprises injecting steam and solvent vapour into the reservoir for mobilizing viscous hydrocarbons in the reservoir and forming a fluid comprising mobilized hydrocarbons, water and solvent; and producing the fluid from the reservoir, wherein the solvent comprises at least one of propane and butane. A molar ratio of the injected solvent to the injected steam is from 0.1 to 3. A mobilizing fluid for use in a solvent-aided process comprises about 40 to about 70 wt% steam; about 30 to about 60 wt% solvent; and less than about 3 wt% methane. The solvent reduces viscosity of viscous hydrocarbons in the reservoir and is more soluble in oil than in water, and has a partial pressure in the reservoir allowing the solvent to be transported as vapour with steam to a steam front.