Abstract: A method for recovering oil from a subterranean, viscous oil-containing formation employing a cyclical injection-production program in which first a mixture of steam and solvent are injected after which fluids including oil are produced until the water cut of the produced fluids reaches 95 percent. Thereafter, the sequence of injection of a solvent/steam mixture and production of fluids including oil is repeated for a plurality of cycles. The ratio of solvent to steam is 2 to 10 volume percent. The mixture of solvent and steam is injected into the lower portion of the formation in which adequate fluid communication exists or in which a communication path is first established. In another embodiment, after the initial solvent/steam injection-production cycle, steam or hot water is injected into the formation followed by production and drawdown of the formation.

Abstract: The sweep efficiency of a steam drive process is improved and steam override reduced significantly if steam is injected into a formation until channeling has begun, after which steam injection is terminated and a slug of a thermally stable diverting fluid comprising a high molecular weight hydrocarbon within the temperature range of 500.degree. to 1000.degree. F. is injected into the steam-swept zone and allowed to cool until the diverting fluid has increased in viscosity to a value greater than the in place oil thereby creating a highly immobile slug in the steam-swept zone. Thereafter, injection of steam is continued and oil recovered. Multiple cycles of steam injection and rejection of slugs of diverting fluid may be repeated to improve sweep efficiency depending upon the vertical thickness of the formation.