Abstract: Significant improvement in the recovery of hydrocarbons from a subterranean hydrocarbon-bearing formation is accomplished by injecting into the formation via an injection well drilled into a formation communicating with an adjacent producing well and containing sandstone and clay components, and aqueous solution of an acid such as hydrochloric acid and a fluorine-containing acid or salt and having dissolved therein an oxyalkylated acrylamido alkanesulfonic acid polymer whereupon the acid solution reacts with the acid soluble components of the formation creating passageways thus facilitating the flow of fluids therein and thereby increasing the recovery of hydrocarbons from the formation through the adjacent production well.

Abstract: 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 usually via casing and cement pack perforations a composition comprising an aqueous solution of a mineral acid having dissolved therein a small amount of a vinylpyrrolidone polymer or an alkoxylated vinylpyrrolidone polymer. The increase in the permeability and porosity of the formation achieved utilizing the method of invention results in a substantial improvement in hydrocarbon recovery. Optionally, the injected composition may be saturated with natural gas at the injection pressure. In another embodiment this invention relates to the oxyalkylated vinylpyrrolidone polymer compositions.

Abstract: 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 usually via casing and cement pack perforations a composition comprising an aqueous solution of a mineral acid having dissolved therein a small amount of a vinylpyrrolidone terpolymer. The increase in the permeability and porosity of the formation achieved utilizing the method of invention results in a substantial improvement in hydrocarbon recovery. Optionally, the injected composition may be saturated with natural gas at the injection pressure.

Abstract: Significant improvement in the recovery of hydrocarbons from a subterranean hydrocarbon-bearing calcareous formation is accomplished by injecting into the formation via an injection well drilled into a formation communicating with an adjacent producing well and containing acid-soluble components which may or may not have water-sensitive clays and shales included therein, a composition comprising an aqueous solution of a mineral acid having dissolved therein a small amount of a vinylpyrrolidone terpolymer solution whereupon the acid solution reacts with the acid-soluble components of the formation creating passageways or enlarging existing passageways thus facilitating the flow of fluids therein and thereby increasing the recovery of hydrocarbons from the formation through the adjacent producing well. Optionally, the injected composition may be saturated with natural gas at the injection pressure.

Abstract: 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 an oxyalkylated acrylamido alkanesulfonic acid polymer. The increase in the permeability and porosity of the formation achieved utilizing the method of invention results in a substantial improvement in hydrocarbon recovery.

Abstract: The production of hydrocarbons from a subterranean hydrocarbon-bearing formation containing acid-soluble components, such as one containing clays or siliceous minerals as exemplified by sandstone, shale, etc. is stimulated by injecting into the formation a composition comprising an aqueous solution of a mineral acid and a fluorine-containing acid or salt and having dissolved therein an oxyalkylated acrylamido alkanesulfonic acid polymer. The indepth increase in the permeability and porosity of the formation achieved utilizing the method of invention results in a substantial improvement in hydrocarbon recovery.

Abstract: Significant improvement in the recovery of hydrocarbons from a subterranean hydrocarbon-bearing calcareous formation is accomplished by injecting into the formation via an injection well drilled into a formation communicating with an adjacent producing well and containing acid-soluble components which may or may not have water-sensitive clays and shales included therein, an acidic aqueous oxyalkylated acrylamido alkanesulfonic acid polymer solution whereupon the acid solution reacts with the acid-soluble components of the formation creating passageways or enlarging existing passageways thus facilitating the flow of fluids therein and thereby increasing the recovery of hydrocarbons from the formation through the adjacent producing well.

Abstract: Significant improvement in the recovery of hydrocarbons from a subterranean hydrocarbon-bearing formation is accomplished by injecting into the formation via an injection well drilled into a formation communicating with an adjacent producing well and containing sandstone and clay components, and aqueous solution of an acid such as hydrochloric acid and a fluorine-containing acid or salt and having dissolved therein an oxyalkylated acrylamido alkanesulfonic acid polymer whereupon the acid solution reacts with the acid soluble components of the formation creating passageways thus facilitating the flow of fluids therein and thereby increasing the recovery of hydrocarbons from the formation through the adjacent production well.

Abstract: A fluid containing a dual surfactant system and a process using the fluid for recovering petroleum from petroleum formations containing high salinity water, e.g. from 50,000 to 225,000 parts per million which may include from about 200 to about 14,000 parts per million polyvalent ions such as calcium and/or magnesium dissolved therein and a method of using said fluid in a surfactant flooding oil recovery process. The surfactant system comprises a water-soluble salt of petroleum sulfonate or an alkyl or alkylaryl sulfonate wherein the alkyl chain may have from 5 to 25 carbon atoms, plus a phosphate ester surfactant with an average molecular weight not to exceed 1000. The surfactant combination is stable up to at least 225.degree. F and resistant to bacterial attack and inhibits scale formation.

Abstract: The production of hydrocarbons from a subterranean hydrocarbon-bearing formation containing acid-soluble components, such as one containing clays or siliceous minerals as exemplified by sandstone, shale, etc. is stimulated by injecting into the formation a composition comprising an aqueous solution of a mineral acid and a fluorine-containing acid or salt and having dissolved therein a vinylpyrrolidone polymer and, if desired, a small amount of a water-soluble acrylic acid-type polymer. The in-depth increase in the permeability and porosity of the formation achieved utilizing the method of invention results in a substantial improvement in hydrocarbon recovery.

Abstract: This invention concerns methods of imparting properties of scale resistance to surfaces upon which adherent scale is normally prone to form during contact with mineralized waters through the use of novel; polyurethane-type resins, characterized by containing pendant polyoxyalkylene chains attached to a basic polyurethane skeletal network.

Abstract: A three surfactant system usable in high temperature petroleum formations containing water having from about 200 to about 14,000 parts per million polyvalent ions such as calcium and/or magnesium dissolved therein and a pH of from 5 to 9, and a method of using said surfactant system for recovering petroleum from high temperature subterranean petroleum-containing formations. The three component surfactant system comprises (1) water-soluble salt of an alkyl or alkylaryl sulfonate wherein the alkyl chain may have from 5 to 25 carbon atoms, (2) a phosphate ester surfactant with an average molecular weight not to exceed 1000, and (3) a surfactant having the following betaine related structure: ##STR1## wherein R is an alkyl group having from 12 to 24 carbon atoms, and n is an integer from one to five. The surfactant combination is stable up to at least 225.degree. F and resistant to bacterial attack and inhibits scale formation.

Abstract: Composition and method for the treatment of inorganic mineral scale, using a treating composition consisting of a water soluble substituted taurine of prescribed formula in an amount of from 0.0005% to about 0.005%, on a weight basis.

Abstract: 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.

Abstract: Composition and method for the treatment of scale, particularly calcium and/or barium sulfate scale, using an alkyl benzene sulfonate, including the alkali metal and ammonium salts thereof, said alkyl group containing from about 8 to about 14 carbon atoms at a concentration of from about 10 to about 50 ppm on a weight basis.

Abstract: 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.

Abstract: A process is provided whereby a subterranean formation may be treated uniformly with acid at a controlled rate to a considerable distance from an injection point. The process includes an introduction of an acid which is solid but will slowly solubilize in water or brine in a subterranean formation. The introduction of the solid acid may take place via fracture fissures in the formation and also if desired in conjunction with a propping agent.

Abstract: A process and composition for the treatment of oil and gas wells to prevent and/or inhibit the build-up of an undesirable inorganic mineral scale deposits in which an aqueous solution of a vinylpyrrolidone polymer is employed in an amount sufficient to prevent and/or inhibit the development of such scale.

Abstract: Composition and method for the treatment of scale, particularly calcium and/or barium sulfate scale, using a treating composition consisting of about one part by weight of a sulfated/sulfonated polyethoxy alkyl phenol containing from about 8 to about 14 carbon atoms in the alkyl group and from about 4 to about 10 ethoxy groups, in admixture with from about 1 to 3 parts by weight of a C.sub.8 -C.sub.14 alkyl benzene sulfonate, including the alkali metal and ammonium salts of one or both compounds, and mixtures thereof.

Abstract: 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.