Texaco Inc.

Conoco Inc.

Russell D Shupe

Jim Maddox, Jr

Jack F Tate

Alfred Brown

Wilbur L Hall

Ching H Wu

A process for removing residual oil from the near wellbore area of a subterranean formation adjacent an injection well of a waterflood operation to improve water injectivity comprising injection through said well into said area seawater containing a surfactant having the formula:

Process for secondary oil recovery utilizing propoxylated ethoxylated

Many petroleum formations contain water having high salinity and/or high concentrations of divalent ions such as calcium or magnesium dissolved therein, and are additionally at temperatures from about 70.degree. F. to about 300.degree. F. Most surfactants suitable for use in oil recovery operations are either ineffective in high salinity or high hardness waters, or cannot tolerate the higher temperatures encountered in many such formations. A water-external phase emulsion, microemulsion or micellar dispersion containing a water soluble alkylpolyalkoxyalkylene sulfonate or alkylarylpolyalkoxyalkylene sulfonate and a water-insoluble polyethoxylated aliphatic alcohol (including alkanols) or polyethoxylated alkylphenol nonionic surfactant is an effective fluid for flooding in formations containing water whose salinity is from 70,000 to 220,000 parts per million total dissolved solids and also having temperatures as high as 300.degree. F. The fluid is phase stable over a wide range of formation temperatures and water salinities and hardness values.

Emulsion oil recovery process usable in high temperature, high salinity

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

Many petroleum-containing formations contain high salinity and/or hard water and have temperatures from 150.degree. F. to 300.degree. F. Many surfactants known for oil recovery purposes may be used in either the high salinity or hard water, or in the presence of high temperature, but few surfactants or surfactant combinations are suitable for use in formations containing both high salinity water and temperatures much in excess of about 150.degree. F. An alkylpolyalkoxyalkyl sulfonate or alkylarylpolyalkoxyalkyl sulfonate, either as the sole constituent of an aqueous surfactant fluid, or as a solubilizing co-surfactant in combination with an anionic surfactant such as a petroleum sulfonate, an alkyl sulfonate, or an alkylaryl sulfonate, is effective for use in formations containing high salinity and/or hard water which are additionally at a temperature from about 70.degree.-300.degree. F. The chain length of the alkyl constituent of the alkylpolyalkoxyalkyl sulfonate or alkylarylpolyalkoxyalkyl sulfonate, as well as the number of alkoxy groups in the surfactant molecule is carefully chosen to achieve limited solubility in a solution having salinity and divalent ion concentration about equal to the formation water at a temperature about equal to the formation temperature. Such solutions are not phase stable at surface ambient temperature if the difference between the formation temperature and the surface ambient temperature is substantially greater than about 100.degree. F. It is necessary to heat the solution to completely dissolve the surfactants therein and to maintain the solution heated to a temperature within at least 100.degree. F. of the formation temperature and preferably within at least 50.degree. F. of the formation temperature when it is injected thereinto.

Surfactant oil recovery process usable in high temperature formations

Many petroleum formations contain water having high salinity and/or high concentrations of divalent ions such as calcium or magnesium dissolved therein, and are additionally at temperature from about 70.degree. F. to about 300.degree. F. Most surfactants suitable for use in oil recovery operations are either ineffective in high salinity or high hardness waters, or cannot tolerate the higher temperatures encountered in many such formations. An aqueous fluid containing a water soluble alkylpolyalkoxyalkyl sulfonate or alkylarylpolyalkoxyalkyl sulfonate and a water-insoluble polyethoxylated aliphatic alcohol or polyethoxylated alkylphenol nonionic surfactant is effective in formations containing water whose salinity is from 70,000 to 220,000 parts per million total dissolved solids and also having temperatures as high as 300.degree. F. The fluid is phase stable over a wide range of formation temperatures and water salinities and hardness values.

Surfactant oil recovery process usable in high temperature, high

Many petroleum formations contain water having excessive quantities of salt or divalent ions such as calcium or magnesium dissolved therein, and are additionally at a temperature from about 70.degree. to about 300.degree. F. Most surfactants otherwise usable for oil recovery operations are either ineffective in high salinity or hard water, or decompose or precipitate at the higher temperature encountered in formations. A sulfonated, ethoxylated alcohol or alkylphenol surfactant, either as the sole constituent of the surfactant solution, or as a co-surfactant with a more conventional anionic surfactant such as petroleum sulfonate, alkyl sulfonate, or alkylaryl sulfonate, is effective for use in formations containing water having substantial amounts of salt and/or divalent ion salts such as calcium or magnesium dissolved therein, and which additionally may be hotter than 120.degree. F.

Composition and method for the treatment of inorganic mineral scale, particularly calcium and/or barium sulfate scale, using a treating composition consisting of a water-soluble sulfonated ethoxylated alkylphenol of prescribed formula in an amount of from about 0.0005 to about 0.005%, on a weight basis.

Method for treating scale

Composition and method for the treatment of inorganic mineral scale particularly calcium and/or barium sulfate scale, using a treating composition consisting of a water-soluble sulfonated ethoxylated alcohol of prescribed formula in an amount of from about 0.0005% to about 0.005%, on a weight basis.

Composition and method for treating scale

The production of hydrocarbons from a subterranean hydrocarbon-bearing formation is stimulated by injecting into the formation an aqueous solution of a compound hereinafter described. The elimination of plugging of capillary openings within the formation and mineral scale deposition on production equipment due to post-precipitation of dissolved salts subsequent to treatment by means of said compound results in a substantial improvement in hydrocarbon recovery.

Method for oil recovery

The production of hydrocarbons from a subterranean hydrocarbon-bearing formation containing acid-soluble components, such as one composed at least in part of dolomite or limestone, is stimulated by injecting into the formation a composition comprising an aqueous solution of a mineral acid having dissolved therein a compound hereinafter described. The elimination of plugging of capillary openings within the formation and mineral scale deposition on production equipment due to post-precipitation of dissolved salts subsequent to acidization by means of the said compound results in a substantial improvement in hydrocarbon recovery.

Method for stimulating well production

The production of hydrocarbons from a subterranean hydrocarbon-bearing formation is stimulated by injecting into the formation an aqueous solution of a compound hereinafter described. The elimination of plugging of capillary openings within the formation and mineral scale deposition on production equipment due to post-precipitation of dissolved salts subsequent to treatment by means of the compound results in the substantial improvement in hydrocarbon recovery.

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Houston, TX, United States of America

Russell D Shupe