Abstract: A steam flooding method for recovering oil from an underground formation penetrated by an injection and at least one production well is modified by initially lowering the permeability of the lower vertical portion of the formation, e.g., by plugging thereof with gravel sand pack, capped by a plaster of paris or cement, thereafter continuing to inject the steam into the injection well and maintaining high level of production from the production well until thermal breakthrough is achieved in the production well. Subsequently, the initial permeability of the lower vertical portion of the formation is restored, e.g., by removing the gravel sand pack, and oil is recovered from the production well. In a preferred embodiment, the permeability of substantially the entire initial completed interval of the production well is decreased in the aforementioned manner, the well is recompleted higher in the formation and steam is continuously injected into the injection well.

Abstract: In a steam flood oil recovery process wherein the oil-containing formation has a natural brine salinity concentration within the range of 10 to 20% by weight, sweep efficiency is improved by injecting steam until steam breakthrough occurs at the production well after which a mixture of steam, a noncondensible gas, and a surfactant comprising a C.sub.12 alpha olefin sulfonate is injected into the formation. The C.sub.12 alpha olefin sulfonate forms a stable foam with the formation oil at formation conditions that reduces the permeability of the highly permeable steam swept zones thereby diverting the steam to other portions of the formation containing unswept oil. If the formation does not contain a natural brine salinity concentration, then the salinity of the mixture of steam, noncondensible and surfactant is controlled to a concentration of about 10% by weight by adding a salt thereto.