Abstract: A foam/steam injection method for forming fractures is a for reservoir penetrated by a horizontal wellbore. Steam is injected into said wellbore at a pressure sufficient to fracture the formation. Water which is used to make the steam contains a foamable composition in an amount sufficient to make a foam upon contact with steam. Steam and foam enter the wellbore and create a fracture in an oil-rich zone. Thereafter, foam blocks further steam entry into the created fracture which causes another fracture to form at a second interval along the horizontal wellbore. These steps are repeated until a fracture system is made along the length of the wellbore.

Abstract: A well completion method is claimed for steam stimulation of a wellbore, either horizontal or vertical, where limited entry perforations are utilized. Limited-entry perforations of specified spacing and size are placed into a closed-end injection tubing. Steam is directed down the tubing and distributed through the perforations which act as steam chokes, under critical flow conditions, thereby causing uniform steam injection and uniform heating along a desired length of a horizontal wellbore.

Abstract: A method for intermittent steam injection which comprises completing wells in more than one zone and selecting a number of wells as steam injectors. As interwell communication (temperature breakthrough) develops, producers are shut-in to allow for the reservoir pressure to build up and heat to propagate from the channel of communication (e.g., fractures) to the reservoir matrix. The injection phase is followed by blowdown. Thereafter, shut in producers and, in certain other cases, injectors are put on production.

Abstract: A process for preventing steam entry into a bottom water zone of a formation. Performations are made in a well which perforations communicate with the lowest level of said bottom water zone. Air is injected into the lowest level of said zone via said well which initiates low temperature oxidation thereby increasing the viscosity of said oil and making a heavy oil. When a desired viscosity is obtained, air injection is ceased. Said well is recompleted and perforations are placed in said well which causes it to communicate with a higher level oil saturated zone. Steam is injected into said higher level since the lowest level of the bottom water zone is closed because of the high viscosity oxidized oil. Thus, steam injection causes oil to be removed from the higher level of said formation.

Abstract: A process for closing pores in a bottom water zone where steam is directed so as to by-pass a zone of the formation containing hydrocarbonaceous fluids. Once a portion of the bottom water zone has reached a temperature in excess of about 300.degree. F., steam entry is ceased. Afterwards, a temperature activated gellable composition is placed into the bottom water zone. When the composition reaches that portion of the bottom water zone where a temperature in excess of about 300.degree. F. has been reached, the composition activates and forms a rigid gel. Thereafter, a steam flooding method is commenced. Steam is diverted from the bottom water zone and into an upper zone containing hydrocarbonaceous fluids.

Abstract: In a CO.sub.2 miscible displacement enhanced oil recovery process, produced CO.sub.2 -hydrocarbon gas containing from more than the maximum CO.sub.2 content tolerable in a fuel gas up to about 70 volume percent CO.sub.2 is reinjected into a small portion of the well pattern volume and produced CO.sub.2 -hydrocarbon gas containing more than 70 volume percent CO.sub.2 is reinjected into a larger portion of the well pattern volume. The method provides a more effective utilization of CO.sub.2 in a CO.sub.2 miscible enhanced oil recovery process while maintaining most of the oil-containing formation under miscible conditions.

Abstract: A method for the recovery of oil from a subterranean, oil-containing formation by a cyclical steam flood-pressurization and production program. During the first cycle, steam is injected into the formation and oil is recovered until there is steam breakthrough at the production well. Thereafter, a pressurization cycle is initiated by throttling or shutting-in the production well while continuing injection of the steam until the bottomhole injection pressure is greater than the vertical pressure created by the overburden thereby causing the formation to fracture horizontally. After the horizontal fracture is formed, the third cycle or production cycle is initiated in which oil is recovered from the formation from either the production well or the injection well or both until the amount of oil recovered is unfavorable.

Abstract: A plurality of production wells penetrate an oil-bearing reservoir in a dipping subterranean formation. Steam injection wells are located up-dip and down-dip of each oil-bearing reservoir. Some time after steam breakthrough in the upper-most one of the production wells, this well is converted to a steam injection well, and the original up-dip steam injection well is shut in. Some time after steam breakthrough in the lower-most one of the production wells, this well is converted to a steam injection well, and the original down-dip steam injection well is shut-in. Some time after steam breakthrough occurs at the remaining up-dip and down-dip production wells, these wells are sequentially converted to steam injection wells, and the preceding up-dip and down-dip steam injection wells are shut in.