Abstract: A viscous oil-bearing formation is produced by a steam flood technique in which the quality of the steam injected into the formation through an injection well is improved in-situ by the generation of an in-situ heat zone which trails along behind the front of the steam flood. This in-situ heat zone is generated by the injection of a non-condensable oxidant which reacts with the residual oil left behind the steam front in the steam swept zone. The oxidant injection is controlled so that the velocity of the heat zone through the formation is no greater than the velocity of the steam front, thereby preventing heat zone breakthrough of the steam front.

Abstract: A method for the recovery of heavy oil from a subterranean silica-containing oil-containing formation comprising treating the formation with a slug of a hot aqueous solution containing sodium hydroxide and sodium bicarbonate capable of forming in-situ CO.sub.2 and metasilicate followed by injection of a drive fluid to aid in recovering the oil.

Abstract: This specification discloses a method for the recovery of oil from a subterranean, viscous asphaltic oil-containing formation comprising injecting a predetermined amount of a solution comprising an aromatic hydrocarbon and an acid selected from the group consisting of phenol, carboxylic acid, and acidic anhydrite. Thereafter, the formation is subjected to a thermal recovery technique such as steam flooding or an in-situ combustion operation and oil is recovered.