Water-in-oil emulsion composition and method of treating subterranean formation using same

Abstract

A method of treating a portion of a subterranean formation that includes: providing a water-in-oil emulsion, inverting the water-in-oil emulsion to form a friction reducing treatment solution, and introducing the treatment solution into the portion of the subterranean formation. The water-in-oil emulsion has an oil phase, an aqueous phase and surfactants. The oil phase (O) and an aqueous phase (A) are present at an O/A ratio of from about 1:8 to about 10:1. The oil phase is present as a continuous phase and contains an inert hydrophobic liquid. The aqueous phase is present as a dispersed phase of distinct particles in the oil phase and includes water and a water soluble polymer. The water soluble polymer makes up from 10 to 25 weight percent of the water-in-oil emulsion. The water-in-oil emulsion is inverted by adding it to water to form a friction reducing treatment solution.

1 . A water-in-oil emulsion having an oil phase (O) 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 and a water soluble polymer, and surfactants; 
   wherein the water soluble polymer is a polymer formed by polymerizing a monomer mixture comprising acrylamide, wherein from about 1% to about 40% of the acrylamide residues are hydrolyzed to form acrylic acid residues or corresponding salts after being polymerized and the water soluble polymer comprises from 10 to 25 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 wt % more water soluble polymer.   
     
     
         2 . (canceled) 
     
     
         3 . (canceled) 
     
     
         4 . The water-in-oil emulsion according to  claim 1 , wherein the water soluble polymer comprises one or more monomers selected from the group consisting of 2-acrylamido-2-methylpropane sulfonic acid, N,N-dimethylacrylamide, vinyl sulfonic acid, N-vinyl acetamide, meth(acrylic acid), acrylic acid, N-vinyl formamide, and/or salts thereof and/or combinations 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 7,500,000 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 1M NaCl solution, at 30° C., pH 7, of from about 10 to about 40 dl/g. 
     
     
         7 . The water-in-oil emulsion according to  claim 1 : 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. 
     
     
         8 . A method of treating a portion of a subterranean formation, comprising:
 Providing the water-in-oil emulsion according to  claim 1 ;   inverting the water-in-oil emulsion by adding it to water at from about 0.1 to about 2 gallons of water-in-oil emulsion per thousand gallons of water to form a friction reducing treatment solution containing from about 0.0025 to less than about 0.1% water soluble polymer based on the weight of the treatment solution; and   introducing the treatment solution into the portion of the subterranean formation.   
     
     
         9 . (canceled) 
     
     
         10 . The method according to  claim 8 , 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. 
     
     
         11 . The method according to  claim 8 , wherein the water-in-oil emulsion comprises at least one of an inhibitor, a salt, or an inverting surfactant. 
     
     
         12 . The method according to  claim 8 : 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 comprises a tall oil fatty acid diethanol amine, a polyoxyethylene (5) sorbitan monooleate, and a sorbitan monooleate. 
     
     
         13 . The method according to  claim 8 , 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 2 gallons of water-in-oil emulsion per thousand gallons of 2% KCl solution (gpt). 
     
     
         14 . The method according to  claim 8 , wherein the water soluble polymer comprises one or more monomers selected from the group consisting of 2-acrylamido-2-methylpropane sulfonic acid, N,N-dimethylacrylamide, vinyl sulfonic acid, N-vinyl acetamide, N-vinyl formamide, meth(acrylic acid), acrylic acid, acrylonitrile, acrylonitrile-dimethyl amine reaction products, or salts thereof and combinations thereof. 
     
     
         15 . A water-in-oil emulsion having an oil phase (O) 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 and a water soluble polymer, and surfactants; 
   wherein the water soluble polymer comprises from 10 to 25 weight percent of the water-in-oil emulsion;   wherein the water soluble polymer is a polymer formed by polymerizing a monomer mixture comprising acrylamide, wherein from about 1% to about 40% of the acrylamide residues are hydrolyzed to form acrylic acid residues or corresponding salts after being polymerized; 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 wt % more water soluble polymer.   
     
     
         16 . (canceled) 
     
     
         17 . The water-in-oil emulsion according to  claim 15 , wherein the water soluble polymer comprises one or more monomers selected from the group consisting of 2-acrylamido-2-methylpropane sulfonic acid, N,N-dimethylacrylamide, vinyl sulfonic acid, N-vinyl acetamide, meth(acrylic acid), acrylic acid, N-vinyl formamide, and/or salts thereof and/or combinations thereof. 
     
     
         18 . The water-in-oil emulsion according to of  claim 15 , wherein the water soluble polymer has a molecular weight in the range of from about 7,500,000 to about 20,000,000. 
     
     
         19 . The water-in-oil emulsion according to  claim 15 , wherein the polymer has a reduced viscosity, as determined in a Ubbelhhde Capillary Viscometer at 0.05% by weight concentration of the polymer in 1M NaCl solution, at 30° C., pH 7, of from about 10 to about 40 dl/g. 
     
     
         20 . The water-in-oil emulsion according to  claim 15 : 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.