Abstract: Oil may be recovered from viscous oil-containing formations including tar sand deposits by providing at least one injection well and at least one spaced-apart production well which extend downwardly from the surface and which extend to, and generally horizontally through, the bottom of the oil-containing formation with fluid communication of the horizontally extending portions of each well with the oil-containing formation. A predetermined amount of solvent, preferably 0.05 to 0.30 pore volume is injected into the bottom of the formation via the injection well and fluids including oil are recovered from the formation via the production well. After the desired amount of solvent has been injected into the formation, production is terminated and both the injection well and production well are shut-in to allow the formation to undergo a soak period for a variable time, preferably for a time between 2 to 20 days per foot of vertical thickness of the oil-containing formation.

Abstract: Disclosed is a method for recovering oil from a dipping subterranean, viscous oil-containing reservoir having an underlying body of water. An in situ combustion operation is initiated using an oxidizing gas injected through an injection well in fluid communication with the lower portion of the reservoir near the oil/water interface. Fluids including oil and effluent gas are recovered from the reservoir through a production well in fluid communication with a shallower portion of the reservoir. After a predetermined amount of time, injection of the oxidizing gas is terminated and the reservoir is allowed to undergo a soaking period for a predetermined amount of time. Thereafter, a water drive is initiated by injecting water into the injection well and fluids including oil are recovered from the reservoir through the production well.