Abstract: Methods of preparing and using stable oil external-aqueous internal emulsions in subterranean formation acidizing, diverting and other treatments are provided. The emulsions can be prepared by batch or continuous mixing by combining the aqueous liquid having a particulated silica compound slurried therein with the oil having a surface active agent which promotes the formation of the emulsion mixed therewith.

Abstract: A method of temporarily reducing fluid loss into a subterranean formation from a well bore penetrating the formation by way of at least one perforation is provided. A first soluble particulate solid material is introduced into the formation by way of the perforation having a particle size whereby it bridges on the face of the formation and fills the perforation but allows fluid flow therethrough. A second soluble particulate solid material is introduced into the well bore having a particle size such that it bridges on the first particulate solid material and forms a seal over the perforation within the well bore.

Abstract: An aqueous acidic composition useful for conducting a formation acidizing method is disclosed. The composition, which is comprised of a blend of acetic acid, formic acid, a fatty alkyl quaternary ammonium salt, a fatty aralkyl quaternary ammonium salt and an alkanoic and/or alkenoic acid having at least four carbon atoms and at least two alcoholic hydroxyl groups per molecule, resists the formation of sludge, and insoluble ferric and calcium compounds.

Abstract: An aqueous acidic composition useful for conducting a formation acidizing method is disclosed. The composition, which is comprised of a blend of acetic acid, formic acid, a fatty alkyl quaternary ammonium salt, a fatty aralkyl quaternary ammonium salt and an alkanoic and/or alkenoic acid having at least four carbon atoms and at least two alcoholic hydroxyl groups per molecule, resists the formation of sludge, and insoluble ferric and calcium compounds.

Abstract: A concentrate which forms an acid internal microemulsion well treatment composition when added to an acid treatment fluid. The concentrate comprises in the range of from about 20% to about 98% by weight of a hydrocarbon carrier fluid, in the range of from about 1% to about 50% by weight of an alkyl alcohol having from 4 to 18 carbon atoms and in the range of from about 1% to about 50% by weight of an emulsifying agent comprising at least one compound selected from the group consisting of sulfate esters, phosphate esters, alkyl aromatic sulfonic acids, amine salts having ester or amide linkages, quaternary ammonium compounds having ester of amide linkages, propoxylated fatty acids, and propoxylated alcohols. Also disclosed are an acid internal microemulsion well treatment composition and a method of treating a subterranean formation to increase the production of hydrocarbons therefrom.

Abstract: A concentrate which forms an acid and/or water external microemulsion when added to a treatment fluid. The concentrate comprises an alkyl alcohol having in the range of from 4 to 18 carbon atoms, an emulsifying agent, a mutual solvent selected from the group consisting of glycol ethers and alkyoxylates of glycol ethers, and a co-solvent selected from the group consisting of polyethylene glycol, primary alcohols and alkyoxylates of alkyl alcohols. Also disclosed are an acid and/or water external microemulsion well treatment composition and a method of treating a subterranean formation to increase the production of hydrocarbons therefrom.

Abstract: A precipitation control additive composition, an acidizing composition for treating a sour well and a method of treating a sour well are provided. An iron sequestering agent and a sulfide modifier are added to a treating solution. The iron sequestering agent combines with iron present in the solution while the sulfide modifier combines with sulfides present in the solution. By combining with both iron and sulfides present in the solution, the combination of an iron sequestering agent and a sulfide modifier effectively inhibits precipitation of ferric hydroxide, ferrous sulfide and free sulfur from the solution. As a result, formation and other serious damage is prevented.

Abstract: A precipitation control additive composition, an acidizing composition for treating a sour well and a method of treating a sour well are provided. An iron sequestering agent, such as aminopolycarboxylic acids, hydroxycarboxylic acids, cyclic polyethers, and derivatives thereof and a sulfide modifier, such as aldehyde, acetal, hemiacetal, and many other compounds capable of forming aldehydes in solution are added to a treating solution. The iron sequestering agent cobines with iron present in the solution while the sulfide modifier combines with sulfides present in the solution. By combining with both iron and sulfides present in the solution, the combination of an iron sequestering agent and a sulfide modifier effectively inhibits precipitation of ferric hydroxide, ferrous sulfide and free sulfur from the solution. As a result, formation and other serious damage is prevented.

Abstract: A method and composition for stimulating subterranean formations containing iron deposits. The composition comprises an admixture of (i) at least one member selected from the group consisting of hydroxylamine hydrochloride, hydroxylamine hydrobromide, hydroxylamine sulfate, hydrazine monohydrochloride, hydrazine dihydrochloride, hydrazine sulfate, hydrazine monobromide, hydrazine dibromide, hydrazine monoiodide, hydrazine diiodide and hydroquinone together with (ii) at least one member selected from the group consisting of gluconodeltalactone, citric acid, salts of citric acid, ethylenediaminetetraacetic acid, salts of ethylenediamianetetraacetic acid, nitrilotriacetic acid, salts of nitrilotriacetic acid, hydroxyethylethylenediaminetriacetic acid, and salts of hydroxyethylethylenediaminetriacetic acid and (iii) a catalytic amount of a solubilized salt of a compound capable of providing cupric, cuprous, nickel, zinc ions or mixtures thereof.

Abstract: A method and composition for stimulating subterranean formations containing iron deposits. The composition comprises a compound comprising at least one member selected from the group consisting of dihydroxymaleic acid, salts of dihydroxymaleic acid and gluconodeltalactone. The method comprises contacting the subterranean formation in an appropriate manner with the above-described composition present in an amount sufficient to sequester iron.

Abstract: The present invention relates to a method of treating a carbonate-containing subterranean formation to increase the production of hydrocarbons therefrom. The subterranean formation is contacted with an aqueous solution of a composition represented by the formula: ##STR1## wherein a is a whole number or fraction thereof in the range of from about 4 to about 18;wherein b is a whole number or fraction thereof in the range of from about 0 to about 30;wherein c is a whole number or fraction thereof in the range of from about 0 to about 3;wherein d is independently a whole number or fraction thereof in the range of from about 0 to about 3;wherein e is a whole number or fraction thereof in the range of from about 1 to about 3;R is independently selected from the group consisting of hydrogen and a methyl group whereby mixtures containing both groups may result; andX.sup.

Abstract: A method of temporarily plugging a subterranean formation using a diverting material comprising an aqueous carrier liquid and a diverting agent comprising a solid azo compound having an azo component and a methylenic component.

Abstract: A composition and method of acidizing or fracturing a subterranean formation comprising contacting the formation with a composition comprising an acid, urea, and a selected gelling agent. The urea is present in an amount sufficient to extend the viscous stability of the gelled acid composition in comparison to the acid and gelling agent alone.

Abstract: The present invention relates to a diverting material or fluid-loss additive for use in subterranean formations penetrated by a well bore comprising graded phthalimide particles. The phthalimide particles are introduced into the formation in a carrier fluid. The carrier fluid can include gelling agents or any of the various salts known to be useful in fluids employed in subterranean formation treatment. The phthalimide particles can be used in elevated temperature oil and gas producing formations.

Abstract: Methods of chemically retarding the reaction rates of acidizing fluids on calcareous formations and chemically retarded acidizing compositions are provided.

Abstract: Methods of acidizing a subterranean well formation, acidizing compositions and sequestering additives for preventing the precipitation of metal compounds in the formation.

Abstract: A well acidizing or fracturing composition is prepared by adding to an aqueous acid solution or emulsion or fracturing composition, a cross-linked copolymer of a sulfonic acid-modified acrylamide and a polyvinyl cross-linking agent. The cross-linked copolymer functions as an effective fluid loss additive and/or diverting agent. From about 25 pounds to about 100 pounds of the additive is utilized per 1000 gallons of the aqueous acid solution or acid emulsion.