Diluted cationic friction reducers

Abstract

A water-in-oil emulsion, having an oil phase (0) and an aqueous phase (A) at an O/A ratio of from about 1:8 to about 10:1, may include the oil phase as a continuous phase that includes an inert hydrophobic liquid, and the aqueous phase as a dispersed phase of distinct particles in the oil phase that includes water, a water soluble polymer, and at least one surfactant: wherein the water soluble polymer includes from about 1 to about 60 weight percent of one or more cationic monomers, wherein the amount is by total weight of the water soluble polymer; wherein the water soluble polymer is present in an amount from about 5 to about 40 weight percent of the water-in-oil emulsion; and wherein an aqueous solution prepared by inverting the water- in-oil emulsion by adding it to water has at least comparable viscosity build to an aqueous solution made from a water-in-oil emulsion of the same composition containing 15 weight percent more water soluble polymer. Also provided is a method of treating a portion of a subterranean formation that includes the steps of: (a) providing a water-in- oil emulsion according to the present disclosure; (b) inverting the water-in-oil emulsion by adding it to water at from about 0.1 to about 5 gallons of water-in-oil emulsion per thousand gallons of water to form a friction reducing treatment solution containing from about 0.0005 weight percent to about 0.12 weight percent water soluble polymer based on the weight of the treatment solution; and (c) introducing the treatment solution into the portion of the subterranean formation.

We claim: 
     
         1 . A water-in-oil emulsion having an oil phase (0) and an aqueous phase (A) at an O/A ratio of from about 1:8 to about 10:1;
 wherein the water-in-oil emulsion includes the oil phase as a continuous phase comprising an inert hydrophobic liquid, and the aqueous phase as a dispersed phase of distinct particles in the oil phase comprising water, a water soluble polymer, and at least one surfactant;   wherein the water soluble polymer comprises from about 1 to about 60 weight percent of one or more cationic monomers, wherein the amount is by total weight of the water soluble polymer;   wherein the water soluble polymer is present in an amount from about 5 to about 40 weight percent of the water-in-oil emulsion; and   wherein an aqueous solution prepared by inverting the water-in-oil emulsion by adding it to water has at least comparable viscosity build to an aqueous solution made from a water-in-oil emulsion of the same composition containing 15 weight percent more water soluble polymer.   
     
     
         2 . The water-in-oil emulsion according to  claim 1 , wherein the cationic monomer is selected from the group consisting of (meth)acrylamidopropyltrimethyl ammonium halides, (meth)acryloyloxyethyltrimethyl ammonium halides, (meth)acryloyloxyethyltrimethyl ammonium methyl sulfate, diallyl dimethyl ammonium halides, diallylamine, methyldiallylamine, dimethylaminoethylmethacrylate, and dimethylaminopropy lmethacrylamide. 
     
     
         3 . The water-in-oil emulsion according to  claim 1 , wherein the water soluble polymer further comprises a non-ionic monomer. 
     
     
         4 . The water-in-oil emulsion according to  claim 3 , wherein the nonionic monomer is selected from the group consisting of C1-C3 alkyl (meth)acrylates, C1-C3 N-alkyl (meth)acrylamide, (meth)acrylamide, N-vinylpyrrolidone, dimethyl(meth)acrylamide, N-vinyl acetamide, and N-vinyl formamide, and salts thereof. 
     
     
         5 . The water-in-oil emulsion according to of  claim 1 , wherein the water soluble polymer has a molecular weight in the range of from about 1,000,000 to about 20,000,000. 
     
     
         6 . The water-in-oil emulsion according to  claim 1 , wherein the polymer has a reduced viscosity, as determined in a Ubbelhhde Capillary Viscometer at 0.05% by weight concentration of the polymer in 1 M NaCl solution, at 30° C., pH 7, of from about 5to about 40 dl/g. 
     
     
         7 . The water-in-oil emulsion according to  claim 3 , wherein the water-in-oil emulsion comprises ammonium salt, 4-methoxyphenol, and an ethoxylated C 12 -C 16  alcohol; and wherein the inert hydrophobic liquid comprises a mixture of paraffinic hydrocarbons and napthenic hydrocarbons; and wherein the surfactants comprise a tall oil fatty acid diethanol amine, a polyoxyethylene (5) sorbitan monooleate, and a sorbitan monooleate; and wherein acrylamide is present in the water soluble polymer in an amount from about 10 weight percent to about 99 weight percent, wherein the amount is by total weight of the water soluble polymer. 
     
     
         8 . A method of treating a portion of a subterranean formation comprising the steps of:
 (a) providing the water-in-oil emulsion of  claim 1 ;   (b) inverting the water-in-oil emulsion by adding it to water at from about 0.1 to about 5 gallons of water-in-oil emulsion per thousand gallons of water to form a friction reducing treatment solution containing from about 0.0005 weight percent to about 0.12 weight percent water soluble polymer based on the weight of the treatment solution; and   (c) introducing the treatment solution into the portion of the subterranean formation.   
     
     
         9 . The method of  claim 7 , wherein the friction reducing treatment solution is introduced into the portion of the subterranean formation at a rate and pressure sufficient to create or enhance one or more fractures in the portion of the subterranean formation. 
     
     
         10 . The method of  claim 7 , wherein the water-in-oil emulsion further comprises at least one additive selected from the group consisting of inhibitors, salts, inverting surfactants, and combinations thereof. 
     
     
         11 . The method of  claim 7 , wherein the water-in-oil emulsion comprises ammonium salt, 4-methoxyphenol, and an ethoxylated C 12 -C 16  alcohol; and wherein the inert hydrophobic liquid comprises a mixture of paraffinic hydrocarbons and napthenic hydrocarbons; and wherein the surfactants comprise a tall oil fatty acid diethanol amine, a polyoxyethylene (5) sorbitan monooleate, and a sorbitan monooleate; and wherein acrylamide is present in the water soluble polymer in an amount from about 10 weight percent to about 99 weight percent, wherein the amount is by total weight of the water soluble polymer. 
     
     
         12 . The method of  claim 7 , wherein the water-in-oil emulsion is present in the friction reducing treatment solution in an amount in the range of from about 0.1 to about 3 gallons of water-in-oil emulsion per thousand gallons of 2% KCI solution (gpt). 
     
     
         13 . The method of  claim 7 , wherein the water soluble polymer comprises one or more monomers selected from the group consisting of (meth)acrylamidopropyltrimethyl ammonium halides, (meth)acryloyloxyethyltrimethyl ammonium halides, (meth)acryloyloxyethyltrimethyl ammonium methyl sulfate, diallyl dimethyl ammonium halides, diallylamine, methyldiallylamine, dimethylaminoethylmethacrylate, and dimethylaminopropylmethacrylamide. 
     
     
         14 . The method of  claim 7 , wherein the water soluble polymer further comprises a non-ionic monomer. 
     
     
         15 . The method of  claim 14 , wherein the non-ionic monomer is selected from the group consisting of C 1 -C 3  alkyl (meth)acrylates, C 1 -C 3  N-alkyl (meth)acrylamide, (meth)acrylamide, N-vinylpyrrolidone, dimethyl(meth)acrylamide, N-vinyl acetamide, N-vinyl formamide, reaction products, salts and combinations thereof.