Viscosifying friction reducers

Abstract

A water-in-oil emulsion that includes 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 that includes an inert hydrophobic liquid, at least one water-insoluble hydrophobic monomer, and at least one surfactant, and the aqueous phase as a dispersed phase of distinct particles in the oil phase that includes water and a water soluble polymer that includes: (i) at least one acrylamide monomer and (ii) at least one acrylic acid monomer; wherein the water soluble polymer is present in an amount from about 10 to about 35 weight percent of the water-in-oil emulsion. Also provided is water-in-oil emulsion that includes 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 that includes an inert hydrophobic liquid and at least one surfactant, and the aqueous phase as a dispersed phase of distinct particles in the oil phase that includes water and a water soluble polymer that includes: (i) at least one acrylamide monomer, (ii) at least one acrylic acid monomer, and (iii) at least one water soluble hydrophobic monomer; wherein the water soluble polymer is present in an amount from 10 to 35 weight percent of the water-in-oil emulsion. Methods of treating a portion of a subterranean formation with a water-in-oil emulsion are also provided.

We claim: 
     
         1 . A water-in-oil emulsion comprising 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, at least one water-insoluble hydrophobic monomer, and at least one surfactant, and
 the aqueous phase as a dispersed phase of distinct particles in the oil phase comprising water and a water soluble polymer comprising: (i) at least one acrylamide monomer and (ii) at least one acrylic acid monomer; 
   
       wherein the water soluble polymer is present in an amount from about 10 to about 35 weight percent of the water-in-oil emulsion. 
     
     
         2 . The water-in-oil emulsion of  claim 1 , wherein the water-insoluble hydrophobic monomer is selected from the group consisting of C 8 -C 18  acrylates. 
     
     
         3 . The water-in-oil emulsion of  claim 2 , wherein the water-insoluble hydrophobic monomer is selected from the group consisting of 2-ethyl hexylacrylate; lauryl acrylate; octyl acrylate; and octadecyl acrylate. 
     
     
         4 . The water-in-oil emulsion of  claim 1 , wherein the water-insoluble hydrophobic monomer is present in an amount from about 0.05 to about 5.0 weight percent of the water-in-oil emulsion. 
     
     
         5 . A water-in-oil emulsion comprising 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 at least one surfactant, and the aqueous phase as a dispersed phase of distinct particles in the oil phase comprising water and a water soluble polymer comprising: (i) at least one acrylamide monomer, (ii) at least one acrylic acid monomer, and (iii) at least one water soluble hydrophobic monomer;   wherein the water soluble polymer is present in an amount from 10 to 35 weight percent of the water-in-oil emulsion.   
     
     
         6 . The water-in-oil emulsion of  claim 5 , wherein the water-soluble hydrophobic monomer is selected from the group consisting of methacrylic ester monomers. 
     
     
         7 . The water-in-oil emulsion of  claim 5 , wherein the water-soluble hydrophobic monomer is present in an amount from about 0.05 to about 5.0 weight percent of the water-in-oil emulsion. 
     
     
         8 . The water-in-oil emulsion of  claim 1 , wherein the surfactant is selected from the group consisting of ethoxylated nonionic surfactants; fatty acid esters of sorbitan;
 tall oil fatty acid diethanolamine; and combinations thereof.   
     
     
         9 . The water-in-oil emulsion of  claim 5 , wherein the surfactant is selected from the group consisting of ethoxylated nonionic surfactants; fatty acid esters of sorbitan;
 tall oil fatty acid diethanolamine; and combinations thereof.   
     
     
         10 . The water-in-oil emulsion 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. 
     
     
         11 . The water-in-oil emulsion of  claim 5 , wherein the water-soluble polymer has a molecular weight in the range of from about 7,500,000 to about 20,000,000. 
     
     
         12 . 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 3 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. 
     
     
         13 . The method of  claim 12 , wherein the water-insoluble hydrophobic monomer is selected from the group consisting of C 8 -C 18  acrylates. 
     
     
         14 . The method of  claim 13 , wherein the water-insoluble hydrophobic monomer is selected from the group consisting of 2-ethyl hexylacrylate; lauryl acrylate; octyl acrylate; and octadecyl acrylate. 
     
     
         15 . A method of treating a portion of a subterranean formation, comprising:
 providing the water-in-oil emulsion according to  claim 5 ;   inverting the water-in-oil emulsion by adding it to water at from about 0.1 to about 3 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. 
     
     
         16 . The method of  claim 15 , wherein the water-soluble hydrophobic monomer is selected from the group consisting of methacrylic ester monomers. 
     
     
         17 . The method of  claim 12 , 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. 
     
     
         18 . The method of  claim 15 , 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. 
     
     
         19 . The method of  claim 12 , wherein the water-in-oil emulsion comprises at least one of an inhibitor, a salt, or an inverting surfactant. 
     
     
         20 . The method of  claim 15 , wherein the water-in-oil emulsion comprises at least one of an inhibitor, a salt, or an inverting surfactant. 
     
     
         21 . The method of  claim 12 , 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% KCl solution (gpt). 
     
     
         22 . The method of  claim 15 , 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% KCl solution (gpt).