Abstract: The vertical conformance of a steam drive process is improved and steam override reduced by utilizing a solvent push-pull process in the lower portion of the formation adjacent the production well. Steam is injected into the injection well with production of fluids from the production well. The production well contains two flow paths from the surface, the first being in fluid communication with the upper portion of the formation. Production is continued until there is a water breakthrough from the formation via the first flow path in the production well. After production via the production well is terminated, a predetermined amount of solvent is injected into the lower portion of the formation via the second flow path in the production well while continuing to inject steam into the injection well.

Abstract: Oil may be recovered from viscous oil-containing formations including tar sand deposits by first establishing a fluid communication path in the lower portion of the formation intermediate at least one injection well and a production well. At least one additional interior production well in fluid communication with the upper portion of the formation is drilled within the formation defined by the injection well and production well. A hydrocarbon solvent having a density less than oil contained in the formation under formation conditions is injected into the fluid communication path via an injection well and fluids including oil are recovered from the production well until solvent is detected in the fluid recovered.