Texaco Inc.

Ching H Wu

Alfred Brown

Wilbur L Hall

Joseph C Allen

Daniel T Konopnicki

Charles D Woodward

Wann-Sheng Huang

Russell D Shupe

Jack H Park

Yick-Mow Shum

Ralph J Korstad

Charles R French

Stephen F Hager

Moutaz Chichakli

A process for enhanced recovery of petroleum from subterranean formations wherein a vapor mixture of steam and a petroleum fraction containing naturally occurring phenolic and carboxylic compounds is injected via an injection well, and a mixture of steam condensate and petroleum is produced via a production well.

Recovering petroleum from subterranean formations

Thermal oil recovery processes employing the injection of steam and/or hot water for mobilizing viscous petroleum sweep only a small fraction of the formation between the wells because of override, underride, or channeling resulting in poor vertical conformance, as well as poor horizontal conformance of the swept portion of the formation. Both vertical and horizontal conformance are improved significantly if steam is injected into a formation until channeling has begun, after which steam injection is terminated and an aqueous fluid is injected into the formation, which has a viscosity essentially the same as water and contains an emulsifying agent capable of forming a viscous emulsion in the portions of the formation where override, underride or channeling has occurred. After a small slug of emulsifying fluid has been injected, steam injection is resumed and as a consequence of the emulsion plug, moves into portions of the formation from which oil would not be recovered if the emulsion had not been injected. Multiple cycles of steam and emulsion injection may be applied to a formation to more completely sweep the full volume of the pattern. Surfactants suitable for use include organic sulfonates such as petroleum sulfonate, and solubilizing co-surfactants such as alkyl or alkylarylpolyethoxyalkylene sulfonates.

High vertical and horizontal conformance thermal oil recovery process

The vertical or both vertical and horizontal conformance of a steam drive process is improved and steam override reduced by penetrating the zone between one injector and one producer, with one or more infill wells in fluid communication with the bottom half or less of the formation, and producing petroleum from the infill well after steam channeling has occurred at the production well. After the water cut of the fluids being produced from the infill well reaches 95 percent, the infill well is converted from a producer to an injector and steam is injected into the infill well and fluids are recovered from the production well. When one infill well is employed in a more or less aligned arrangement between injection and production wells, the vertical conformance is improved. When one or more infill wells are positioned in an offset or nonaligned arrangement relative to each injector and producer, conformance in both the horizontal and vertical planes is improved. By this multi-step process involving the infill wells, the amount of oil recovered from the portion of the formation in the recovery zone defined by the injection and production well is increased significantly.

High vertical conformance steam drive oil recovery method

A method for recovering viscous hydrocarbons from subterranean formations involves injecting a hydrocarbon solvent into the formation at spaced intervals to produce permeable regions or streaks in the formation. The injection is preferably directed to those regions of highest oil saturation, i.e., those regions with lowest effective permeability. A subsequent introduction of a heated fluid then will enable recovery of the viscous hydrocarbons in the treated regions and the untreated zones therebetween.

Method of recovering hydrocarbons by improving the vertical conformance

A process for enhanced recovery of petroleum from subterranean formations is disclosed, wherein steam is injected into a formation via an injection well, and a mixture of petroleum and steam condensate is produced via a production well, wherein the produced mixture is flashed for production of a steam-distilled hydrocarbon fraction, and wherein the steam distilled hydrocarbon fraction is injected, with additional steam, into a subterranean formation for increased recovery of petroleum. The process disclosed is particularly useful in recovery of heavy (low API gravity) petroleum.

Disclosed is a method for recovering viscous oil from subterranean, viscous oil containing formations, particularly from shallow formations which overlie water zones. The production well is completed in the entire oil zone and small amount in the water zone. At least two separate injection means are established in the injection well, the first being in communication with the lower part of the oil formation and upper part of the water formation, with the second injection means being in communication with the upper part of the oil formation. Heated air is injected via the first injection means into the lower part of the oil formation near the oil-water interface, the air channeling through the upper part of the water zone and causing an in situ combustion reaction to occur at the oil water contact. Air injection supports an in situ combustion reaction in the oil water contact zone which heats the oil above by conduction as well as hot gas convection through the oil saturated interval. Steam is then injected into the upper portion of the oil saturated interval by the second injection means while continuing injecting air into the lower portion of the formation to expand the burned out zone upward.

Method for recovering viscous petroleum

Polymer flooding is an effective means of increasing the sweep efficiency of a displacement process for recovering petroleum from a subterranean, petroleum containing formation; however, most polymers suitable for use in flooding operations hydrolyze or otherwise decompose at temperatures above about 150.degree. F to 200.degree. F, and the temperature of many subterranean petroleum-containing formations is in excess of 150.degree. F-200.degree. F. Polymers may be employed in tertiary recovery in formations whose temperatures are greater than the temperature stability limit of the polymer if the formation temperature is first reduced by introducing an aqueous fluid such as water at a temperature substantially below the temperature limit of the polymer into the formation for a period of time sufficient to reduce the formation temperature to a value at or below the temperature tolerance level of the polymer.

Method of treating a high temperature formation to permit the use

Oil is recovered from an oil-bearing subterranean formation penetrated by an injection well and a production well by injecting into the formation via the injection well a solution of a normally solid polymerized methacrylate and oil displaced by the injected solution is recovered from the formation via the production well. Optionally, after the solvent solution has been injected, a hydrocarbon slug such as crude oil, petroleum distillate, a soluble oil composition, etc. may be injected and, if desired, this may be followed by injection of water.

Secondary oil recovery process

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 a process involving injecting into the formation a multiple-component solvent for the petroleum and a thermal fluid. 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 hydrocarbons or aromatic hydrocarbons such as benzene. The multiple solvent injection is continued with no production until the pressure is from 50 to 250% above the vapor pressure of the solvent, at which pressure the solvent mixture is substantially all in the liquid phase. Recovery of petroleum and solvent is from a remotely located well by reducing the pressure in the portion of the formation contacted by the solvents to a value from 5 to 100% above the vapor pressure of the gaseous solvent. A fluid heated to a temperature above the boiling point of the solvent, such as steam, is then injected into the same well as was used for solvent injection. The heated fluid raises the temperaure of the solvent on contact therewith, causing vaporization of the gaseous component, which gaseous solvent expands to force viscous petroleum with liquid solvent dissolved therein toward the production well. In formations having oil saturation greater than 50%, this oil saturation should first be reduced to a value below 50% to prevent plugging.

Combined multiple solvent and thermal heavy oil recovery

Disclosed is a method for recovering viscous oil from subterranean, viscous oil containing formations, particularly from shallow formations which overlie water zones. An injection well is completed in the lower part of the oil formation and an equivalent amount in the water zone immediately therebelow, and the production well is completed in the entire oil zone and small amount in the water zone. Heated air is injected into the formation, the air channeling through the upperpart of the water zone and causing an in situ combustion reaction to occur at the oil water contact. Air injection and in situ combustion in the oil water contact heat the oil above by conduction as well as hot gas convection through the oil saturated interval. The injection well is then completed in the upper portion of the formation and the section in the water zone is closed as by cementing, and then steam is injected into the oil saturated interval.

Recovery of viscous petroleum from thick formations is especially difficult because thermal fluids or solvents needed to mobilize the viscous petroleum tend to channel through high permeability streaks in the formation, thereby bypassing large portions of the petroleum saturated formation. By forming or ensuring that there are naturally occurring high permeability strata in the upper portion and in the lower portion of the petroleum formation, and establishing separate communication means between the surface of the earth and the upper and lower high permeability strata, effective downward displacement may be achieved. A heated fluid such as steam is injected into one well in fluid communication with the lower high permeability strata to pass horizontally through the high permeability strata to another well which is also in fluid communication with the lower high permeability strata, sufficient to heat the lower high permeability zone to a temperature substantially above the ambient temperature of the formation. A solvent having a boiling point intermediate between the ambient temperature of the formation and the temperature to which the communication path is heated is injected into the heated communication path. The solvent vaporizes and moves up into the formation immediately thereabove to dissolve into the viscous petroleum. A gaseous substance is then injected into the upper high permeability strata to increase the pressure therein sufficiently to displace the mixture of viscous petroleum and solvent downward into the lower high permeability strata, wherein it is displaced horizontally to a remotely located well for recovery to the surface of the earth.

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.

Multiple solvent heavy oil recovery method

This invention relates to a method for treating wells completed in subterranean formations which contain unconsolidated sand particles, so as to form a permeable barrier which will permit the flow of liquids therethrough while restraining the flow of the unconsolidated sand particles into the well bore. The method comprises saturating sand adjacent the well bore to be treated with petroleum having a high asphaltic content and optionally thereafter contacting the asphaltic petroleum with a solvent capable of solubilizing non-asphaltic fractions of the petroleum and precipitating or causing deposition of the asphaltic or bituminous portions of the petroleum. A heated fluid such as steam is thereafter injected into the formation to cause solidification of the asphaltic materials which effectively binds the sand grains together to form a porous mass which will effectively restrain the movement of sand particles in the well bore upon subsequently placing the well on production. Suitable hydrocarbon materials for causing precipitation of the asphaltic or bituminous portions of the petroleum include liquid paraffinic hydrocarbons such as butane, pentane, or hexane, N-methyl-2-pyrrolidone and furfural. Steam or a mixture of steam and non-condensable gas such as nitrogen, or mixture of steam and air are then injected into the formation to dehydrate and otherwise solidify the precipitated asphaltic material.

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Golden, CO, United States of America

Ching H Wu