Texaco Inc.

Mohan V Kudchadker

Lawrence E Whittington

James E Varnon

Thad O Walker

Alfred Brown

Vernon H Schievelbein

George Kalfoglou

William Schoen

James W Hughes

Nancy G Dunn

Martha S Doster

Walter J Weiss

Jean B Allison

Disclosed is a surfactant waterflooding oil recovery process for use in high salinity water-containing formations employing two separate surfactant-containing slugs or a single slug in which the composition is changed from the first to the last portion of the slug injected into the formation. The first portion of the surfactant fluid contains a surfactant combination which exhibits optimum low surface tension characteristics, and the second or latter portion of the surfactant slug contains a blend of surfactants which produces a high viscosity fluid. Use of hydrophilic viscosity-increasing polymer is thus avoided, eliminating the interaction between polymer and surfactant which causes a reduction in surfactant effectiveness.

Surfactant waterflood oil recovery process

Disclosed is a method for conducting an enhanced oil recovery process comprising injecting an oil displacing fluid into an injection well and recovering petroleum displaced by the fluid from one or more spaced-apart production wells, by an improved method in which the sweep efficiency or horizontal conformance of the displacement process is increased. A fluid is injected into the producing well, which fluid has a viscosity not substantially greater than the viscosity of water at the conditions of injection, but which reacts with oil present in the formation, forming a viscous emulsion which restricts the flow of fluids through the portion of the formation contacted by the emulsion-forming fluid. As a result of this treatment, there is a reduction in tendency for the displaced and injected fluids to form cusps as they approach the production well, thereby failing to sweep substantial portions of the formation. The injected fluid contains one or more surfactants specifically tailored to form a viscous emulsion with the particular formation crude oil and formation water or brine exhibiting maximum viscosity at formation conditions. The viscous emulsion-forming fluid may be injected into all of a group of wells surrounding a central injection well in approximately equal amounts, for the purpose of improving sweep efficiency, or the treatment may be selectively applied to certain of the wells where the formation exhibits a preferred direction of permeability, or where for other reasons the pattern integrity is poor.

High sweep efficiency enhanced oil recovery process

Treatment of emulsions of oil and water produced from surfactant recovery operations whereby the produced emulsions containing surfactants are demulsified and the surfactants are recovered in the water phase.

Demulsification of emulsions produced from surfactant recovery

An improved surfactant waterflood method for the recovery of oil from a subterranean reservoir utilizing an anionic surface-active agent wherein an aqueous postflush slug containing a nonionic solubilizer is employed to minimize retention of the surface-active agent in the reservoir matrix.

Surfactant waterflood method for the recovery of oil

The dialkylbenzene polyethoxy alkyl sulfonate is combined with a water soluble petroleum sulfonate surfactant to form an effective surfactant solution that is stable in high salinity environments. The surfactant solution is injected into an underground petroleum reservoir in order to recover crude oil therefrom.

Oil recovery method utilizing a dialkyl phenol polyethoxy alkyl

In a surfactant flooding process for recovering oil from a subterranean petroleum reservoir, surfactant loss by adsorption onto the mineral grains of the reservoir matrices is reduced by the addition to the surfactant solution of a sacrificial agent selected from the group consisting of polybasic carboxylic acids, their water soluble salts and mixtures thereof.

Sacrificial agents for petroleum recovery processes

The conformance of an enhanced oil recovery process, including water flood, surfactant or other chemicalized water flood process, in a formation containing at least two zones of varying permeability, the permeability of one zone being at least 50 percent greater than the permeability of the other zone, is improved by flooding until the higher permeability zone has been depleted, after which a fluid is injected into the high permeability zone, said fluid having relatively low viscosity at the time of injection and containing a mixture of surfactants or surface active agents which promote the formation of a coarse emulsion in the flow channels of the formation which reduces the permeability of the high permeability zone. Since the viscosity of the fluid injected into the previously flooded, high permeability zone is no greater than water, it is injected easily into the zone and moves through substantially the same flow channels as water would move in the formation. After the permeability of the first zone has been reduced substantially, water flooding may then be accomplished in the second zone which was originally not invaded by the injected water since its permeability was substantially less than the permeability of the first zone.

High conformance enhanced oil recovery process

The conformance of a water flood oil recovery process, including surfactant or other chemicalized water flood process, in a formation containing at least two zones of varying permeability, the permeability of one zone being at least 50 percent greater than the permeability of the other zone, is improved by flooding until the higher permeability zone has been depleted, after which a fluid is injected into the high permeability zone, said fluid having relatively low viscosity at the time of injection and containing surface active agents which promote the formation of a coarse emulsion in the flow channels of the formation which reduces the permeability of the high permeability zone. Since the viscosity of the fluid injected into the previously water flooded, high permeability zone is no greater than water, it is injected easily into the zone and moves through substantially the same flow channels as water would move in the formation. After the permeability of the first zone has been reduced substantially, water flooding may then be accomplished in the second zone which was originally not invaded by the injected fluid since its permeability was substantially less than the permeability of the first zone. The surface active agent is tailored to exhibit optimum emulsion formation properties with the particular aqueous fluid present in the flow channels of the formation to be treated. The optimum emulsifying surfactant comprises a mixture of an alkylpolyalkoxyalkylene sulfonate or an alkylarylpolyalkoxylalkylene sulfonate and an organic sulfonate such as petroleum sulfonate.

The conformance of an enhanced oil recovery process, including waterflood, surfactant or other chemicalized water flood process, in a formation containing at least two strata or zones of varying permeability, the permeability of one zone being at least 50 percent greater than the permeability of the other zone, is improved by flooding until the higher permeability zone has been depleted, after which an aqueous fluid is injected into the high permeability zone, said fluid having relatively low viscosity at the time of injection and containing a blend of surface active agents which promote the formation of a coarse viscous emulsion in the flow channels of the formation which reduces the permeability of the high permeability zone. After the permeability of the first zone has been reduced substantially, flooding may then be accomplished in the second zone which was originally not invaded by the injected oil recovery fluid. The surface active agents are individually tailored and the ratio of dissimilar surfactants balanced to exhibit optimum viscous emulsion formation properties. The optimum emulsifying surfactant comprises a mixture of an organic sulfonate such as petroleum sulfonate and a solubilizing co-surfactant such as an alkyl or alkylarylpolyalkoxy alkylene sulfonate and/or a low molecular weight alcohol.

High conformance oil recovery process

A process for producing petroleum from subterranean formations is disclosed wherein production from the formation is obtained by driving a fluid from an injection well to a production well. The process involves injecting via the injection well into the formation an aqueous solution of sulfomethylated lignite salt as a sacrificial agent to inhibit the deposition of surfactant and/or polymer on the reservoir matrix. The process may be carried out by first injecting the sulfomethylated lignite salt into the formation through the injection well and following them with either a polymer or a surfactant solution which may also contain sulfomethylated lignite salt. The polymer and/or surfactant would then be followed by a drive fluid such as water to push the chemicals to the production well.

Sulfomethylated lignite salt as a sacrifical agent in oil recovery

A process for producing petroleum from subterranean formations is disclosed wherein production from the formation is obtained by driving a fluid from an injection well to a production well. The process involves injecting into the formation via the injection well an aqueous solution of alkoxylated asphalts as a sacrificial agent to inhibit the deposition of surfactant and/or polymer on the reservoir matrix. Normally the process would be carried out by first injecting the alkoxylated asphalts into the formation through the injection well and following them with either a polymer or a surfactant solution.

Alkoxylated asphalt as sacrificial agents in oil recovery processes

Ethoxylated asphalt solutions have high tolerance for sodium and calcium ions as well as magnesium and other divalent ions. The use of ethoxylated asphalts in combination with other surfactants that normally precipitate out in the presence of these cations results in a stable surfactant solution wherein the surfactant will not precipitate out and wherein the surfactant solution has the ability to efficiently sweep oil from subterranean hydrocarbon reservoirs.

Alkoxylated asphalts as co-surfactants in surfactant oil recovery

A process for producing petroleum from subterranean formations is disclosed wherein production from the formation is obtained by driving a fluid from an injection well to a production well. The process involves injecting into the formation via the injection well an aqueous solution of ethoxylated asphalts as a sacrificial agent to inhibit the deposition of surfactant and/or polymer on the reservoir matrix. Normally the process would be carried out by first injecting the ethoxylated asphalts into the formation through the injection well and following them with either a polymer or a surfactant solution. The polymer and/or surfactant would then be followed by a drive fluid such as water to push the chemicals to the production well.

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Houston, TX, United States of America

Mohan V Kudchadker