Texaco Inc.

Issam S Bousaid

Benny K-c Ho

Alfred Brown

Ralph J Korstad

Thomas W Norman

Marc F Fontaine

Donald L Hoyt

The invention is an in situ combustion method wherein a combustion front is quenched by the injection of water and reignited after quenching by the injection of an oxygen-containing gas and any necessary heat. The quenching of the combustion drive is repeated several times.

Oil recovery by quenched in situ combustion

The invention process is a method of conducting in situ combustion in heavy oil or tar sand reservoirs wherein carbon dioxide is injected into the formation prior to, during, or prior to and during in situ combustion. The carbon dioxide may be injected concurrently with the injection of the oxygen-containing gas or the oxygen-containing gas and carbon dioxide may be injected in alternate slugs. The injection of carbon dioxide aids in situ combustion by lowering the viscosity of the oil, creating channels in the heavy oil deposits for the passage of the oxygen-containing gas and increasing the mobility of oil ahead of the combustion front.

Carbon dioxide injection with in situ combustion process for heavy oils

This invention comprises two steps for improving in situ combustion in shallow reservoirs: (1) use small well patterns preferably with injection to producing wells distance about 200 to 250 feet; and (2) after the front reaches a distance where the air flux is about 5 SCF/(ft.sup.2 -hr), or expressed another way, where the rate of frontal advance is about 0.4 ft/day, allow the air to 'ride' on top of the pay zone while simultaneously water is injected at the oil-water contact below the air entry at the sand face of the injection well.

Recovery of heavy crude oil from shallow formations by in situ combustion

Disclosed is a petroleum recovery method suitable for recovering petroleum from subterranean formations containing water having high salinity and/or divalent ion concentration, employing an aqueous surfactant-containing fluid which is designed to effect low surface tension displacement of petroleum in the formation in the presence of high salinity water. The improvement comprises injecting the total desired volume of surfactant in the form of a plurality of relatively small slugs of surfactant fluid, and alternatingly injecting similarly small pore volume slugs of fresh water having salinity less than the salinity of the formation water. The total pore volume of surfactant-containing fluid injected is ordinarily from 0.01 to 1.00 and preferably from 0.20 to 0.50 pore volumes. This total amount of surfactant fluid is injected in from 2 to 15 and preferably from 3 to 6 separate discrete slugs. Each slug of surfactant fluid is followed by injecting a quantity of low salinity, relatively fresh water, e.g. of salinity less than about 10,000 and preferably less than 1000 parts per million total dissolved solids. The volume of each lower salinity water isolating slug is less than 0.5 and preferably in the range of 0.05 to 0.20 pore volumes.

Oil recovery method employing alternate slugs of surfactant and fresh

Disclosed is a petroleum recovery method useful for recovering petroleum from subterranean formations containing water having high salinity and/or divalent ion concentration, employing an aqueous surfactant-containing fluid which is designed to effect low surface tension displacement of petroleum in the formation in the presence of high salinity water. The improvement comprises injecting the total desired volume of surfactant in the form of a plurality of relatively small slugs of surfactant fluid, and alternatingly injecting similarly small pore volume slugs of fluid comprising fresh water, e.g. salinities less than 10,000 parts per million and preferably less than 1000 parts per million total dissolved solids, and having dissolved or dispersed therein an effective amount of a sacrificial agent such as a water soluble lignosulfonate salt. The total pore volume of surfactant-containing fluid injected is ordinarily from 0.01 to 1.00 and preferably from 0.20 to 0.50 pore volumes. This total amount of surfactant fluid is injected in from 2 to 15 and preferably from 3 to 6 separate discrete slugs. Each slug of surfactant fluid is followed by injecting a quantity of fresh water containing the sacrificial agent. The volume of each fresh water sacrificial agent slug is ordinarily from 0.5 to 5.0 and preferably 1 to 2 times the volume of the preceding surfactant fluid slug.

Disclosed is a petroleum recovery method for recovering petroleum from subterranean formations containing water having high salinity and/or divalent ion concentration, employing an aqueous surfactant-containing fluid which is designed to effect low surface tension displacement of petroleum in the formation in the presence of high salinity water. The improvement comprises injecting the total desired volume of surfactant in the form of a plurality of relatively small slugs of surfactant fluid, and alternatingly injecting similarly small pore volume slugs of fresh, low salinity solution of hydrophilic polymer. The total pore volume of surfactant-containing fluid injected is ordinarily from 0.01 to 1.00 and preferably from 0.20 to 0.50 pore volumes. This total amount of surfactant fluid is injected in from 2 to 15 and preferably from 3 to 6 separate discrete slugs. Each slug of surfactant fluid is followed by injecting a quantity of low salinity, relatively fresh water solution of polymer, e.g. of salinity less than about 10,000 and preferably less than 1000 parts per million total dissolved solids. The volume of each slug of lower salinity polymer solution is ordinarily from 0.5 to 5.0 and preferably 1 to 2 times the volume of the preceding surfactant fluid slug.

Disclosed is a petroleum recovery method useful for recovering petroleum from subterranean formations containing water having high salinity and/or divalent ion concentration, employing an aqueous surfactant-containing fluid which is designed to effect low surface tension displacement of petroleum in the formation in the presence of high salinity water. The improvement comprises injecting the total desired volume of surfactant in the form of a plurality of relatively small slugs of surfactant fluid, and alternatingly injecting similarly small pore volume slugs of fluid comprising fresh water, e.g. salinities less than 10,000 parts per million and preferably less than 1000 parts per million total dissolved solids. The surfactant fluid comprises water containing at least one surfactant and up to 5.0 volume percent hydrocarbon, said hydrocarbon optionally containing an oil soluble silicone compound dissolved therein. The total pore volume of surfactant-containing fluid injected is ordinarily from 0.01 to 1.00 and preferably from 0.20 to 0.50 pore volumes. This total amount of surfactant fluid is injected in from 2 to 15 and preferably from 3 to 6 separate discrete slugs. Each slug of surfactant fluid is followed by injecting a quantity of fresh water. The volume of each fresh water slug is ordinarily from 0.5 to 5.0 and preferably 1 to 2 times the volume of the preceding surfactant fluid slug.

Oil recovery method employing alternate slugs of surfactant fluid and

An in-situ combustion method for oil recovery from a subterranean oil-bearing formation traversed by a plurality of wells comprising a series of well pattern units wherein air permeability is established sequentially in the individual well pattern units pior to the initiation of in-situ combustion, thereby resulting in an increase in overall sweep efficiency.

Method for preconditioning a subterranean oil-bearing formation prior to

A process for recovering oil from a subterranean reservoir in which a slug comprising a hydrocarbon-in-water emulsion together with a small amount of surfactant injected into the formation via an injection well is forced through the formation and oil is recovered via a production well penetrating the formation. In this process an emulsion slug is employed in which the surfactant concentration is tapered by increasing the concentration of the surfactant either incrementally, gradually or by any other convenient method during the slug injection time.

Oil recovery process using an emulsion slug with tapered surfactant

A process for recovering oil from a subterranean reservoir in which a surfactant slug injected into the formation via an injection well is passed through the formation and oil is recovered via a production well penetrating the formation. In this process a tapered surfactant concentration slug is employed in which the surfactant concentraction is increased, either incrementally or gradually, during the slug injection time.

Oil recovery process using a tapered surfactant concentration slug

Petroleum may be recovered from subterranean, petroleum-containing formations by injecting into the formation an organic liquid having dispersed therein, an alkali metal in very fine, preferably colloidal size range, particular form. The organic liquid containing the alkali metal dispersion is followed by injecting an aqueous fluid to react with the alkali metal, generating alkali metal hydroxide, hydrogen gas and heat in the formation which stimulates displacement of the petroleum by encouraging formation of low viscosity oil-in-water emulsions, as well as by thermal viscosity reduction effects, and dissolution of hydrogen gas in the viscous petroleum. The organic liquid having alkali metal dispersed therein may be preceded or followed by injecting crude petroleum from another formation which is prone to emulsify spontaneously and aid in the formation of low viscosity oil-in-water emulsions. Liquids containing emulsifying agents may also be used in combination with the present process, injected either in advance of or after injection of the organic liquid having alkali metal particles dispersed therein. Alkali metals suitable for use in this invention include sodium, potassium and lithium. This process may be used in combination with thermal stimulation processes including steam and/or hot water injection.

Oil recovery process by in situ emulsification

A process for recovering oil from a subterranean reservoir in which a slug comprising an aqueous polymer solution containing a small amount of surfactant injected into the formation via an injection well is forced through the formation and oil is recovered via a production well penetrating the formation. In this process the concentration of the surfactant in the slug of the aqueous polymer solution is tapered by increasing the concentration of the surfactant either incrementally, gradually or by any other convenient method during the slug injection time.

Oil recovery process using a polymer slug with tapered surfactant

A method for the recovery of low gravity viscous oil or bitumens from a subterranean formation by the injection of a mixture of an oxygen-containing gas and hot water or steam into either the upper or lower section of the formation wherein the ratio of oxygen to water is used to control the oxidation temperature.

Recovery of oil by a combination of low temperature oxidation and hot

A method for operating an in situ combustion process in a petroleum containing reservoir wherein a plurality of air injection wells are spaced so that the approximate distance between the wells will be twice the distance at which the flux of air to the burning front from a single injection well becomes negligible.

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Houston, TX, United States of America

Issam S Bousaid