The present invention is directed to a method of oil recovery wherein a miscibility-generating fluid and a reservoir-heating medium are injected into an oil-bearing formation for which it was heretofore believed miscibility could not be generated. By injecting the heating medium, such as steam, with a miscibility-generating fluid, the minimum miscibility pressure of the fluid is lowered and miscibility is effected at a reservoir pressure below the fracture pressure of the formation.

The disclosed invention is a method for efficiently recovering viscous petroleum from hydrocarbon formations, particularly consolidated tar sand formations. A superheated paraffinic solvent under elevated pressure and temperature is injected into the formation. Thereafter, the formation is rapidly produced until pressure is depleted. The injection and production depletion cycle is then repeated.

Disclosed is a method of producing viscous hydrocarbons from a viscous petroleum-containing subsurface formation. At least an injection well and a production well are provided to extend from the surface of the earth into the subsurface formations. A high mobility, brine-filled channel is established through the lower portion of the subsurface formation to communicate with the injection and production well. After the high mobility channel is established, a solvent for the petroleum is injected into the high mobility channel. The injection of the solvent is continued until breakthrough of the solvent at the production well and thereafter until the ratio of petroleum to solvent produced from the production well becomes unfavorable. Thereafter, gas is injected into the high mobility channel to displace the solvent and petroleum from the formation to the production well.