Texaco Inc.

Charles D Woodward

Joseph C Allen

Alfred Brown

Ching H Wu

Petroleum materials may be effectively recovered from subterranean, viscous, asphaltic or bituminous formations such as tar sand deposits by first injecting into the tar sand formation a paraffinic hydrocarbon at a temperature below 300.degree. F which precipitates asphaltic material from the asphaltic petroleum in the formation. Next, solvent injection is terminated and air is injected into the formation, and the formation is ignited to accomplish in situ combustion within the tar sand reservoir utilizing the precipitated asphaltic materials for fuel for the in situ combustion reaction. Reaction temperatures higher than normal in situ combustion temperatures are produced, facilitating thermal cracking and in situ hydrogenation to up grade the produced crude within the tar sand reservoir.

Recovery of petroleum from viscous asphaltic petroleum containing

Viscous petroleum may be recovered from viscous petroleum-containing formations including tar sand deposits by contacting the formation with a heated multiple-component solvent for the petroleum. At least one solvent component is normally gaseous material such as methane, ethane, propane or butane and at least one component is normally liquid, such as pentane and higher molecular weight hydrocarbons. The solvent mixture is heated to a temperature in excess of ambient temperature, and preferably from 100.degree. to 500.degree. F. prior to injection into the formation. The multiple solvent is introduced under sufficient pressure that it is substantially all liquid at the injection conditions. Recovery of petroleum and solvent may be from the same well as is used for injection or from a remotely located well. When the pressure in a portion of the formation contacted by the solvents is reduced below the bubble point pressure of the solvent-bitumen solution, the solvents vaporize to provide a solution gas oil recovery mechanism. The normally liquid components dissolve in the petroleum and reduce the petroleum viscosity.

Heated multiple solvent method for recovering viscous petroleum

Petroleum may be recovered from viscous petroleum-containing formations including tar sand deposits by injecting into the formation a multiple-component solvent for the petroleum. At least one solvent component is gaseous at the temperature and pressure of the petroleum reservoir such as carbon dioxide, methane, ethane, propane, butane or pentane and at least one component is liquid at the reservoir conditions, such as hexane and higher molecular weight aliphatic or aromatic hydrocarbons. The multiple solvent is preferably introduced under sufficient pressure that it is substantially all in the liquid phase. Recovery of petroleum and solvent may be from the same well as is used for injection or from a remotely located well. When the pressure in a portion of the formation contacted by the solvents is reduced below the vapor pressure of the gaseous solvent, it vaporizes to provide drive energy for oil production. The liquid components dissolve in the petroleum and reduce the petroleum viscosity.

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Houston, TX, United States of America

Charles D Woodward