Method of treating a formation

1. A method of treating a portion of a subterranean formation, comprising:

providing 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 which is a continuous phase and comprises an inert hydrophobic liquid, the aqueous phase which is a dispersed phase of distinct particles in the oil phase and comprises 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;

inverting the water-in-oil emulsion by adding it to water to form a friction reducing treatment solution; and

introducing the treatment solution into the portion of the subterranean formation;

wherein the treatment solution provides at least comparable viscosity build to a treatment solution made from a water-in-oil emulsion of the same composition containing 15 wt % more water soluble polymer.

2. The method according to claim 1 , wherein the water soluble polymer is a polymer formed by polymerizing a monomer mixture comprising about 60% to about 99% by weight acrylamide and about 1% to about 40% by weight acrylic acid or its corresponding salts.

3. The method according to claim 1 , 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 its corresponding salts after being polymerized.

4. The method according to claim 1 , wherein the friction reducing treatment solution contains the polymer in an amount of from about 0.0025% to about 4% based on the weight of the solution.

5. The method according to of claim 1 , wherein the polymer has a molecular weight in the range of from about 7,500,000 to about 20,000,000.

6. The method according to of 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 method according to claim 1 , 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.

8. The method according to claim 1 , wherein the water-in-oil emulsion comprises at least one of an inhibitor, a salt, or an inverting surfactant.

9. The method 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 comprises 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 in the range of from about 60% to about 80% by weight of the polymer.

10. The method according to claim 1 , 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).

11. The method 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, N-vinyl formamide, meth(acrylic acid), acrylic acid, acrylonitrile, acrylonitrile-dimethyl amine reaction products, corresponding salts thereof and combinations thereof.

12. A method of treating a portion of a subterranean formation, comprising:

providing 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 which is a continuous phase and comprises an inert hydrophobic liquid, the aqueous phase which is a dispersed phase of distinct particles in the oil phase and comprises water and a water soluble polymer, and surfactants, wherein the water soluble polymer comprises from 15 to 25 weight percent of the water-in-oil emulsion

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.

13. The method according to claim 12 , wherein the water soluble polymer is a polymer formed by polymerizing a monomer mixture comprising about 60% to about 99% by weight acrylamide and about 1% to about 40% by weight acrylic acid or its corresponding salts.

14. A method of treating a portion of a subterranean formation, comprising:

providing a water-in-oil emulsion comprising an oil phase (O), an aqueous phase (A) at an O/A ratio of from about 1:8 to about 10:1, and surfactants;

wherein the oil phase is a continuous phase and comprises an inert hydrophobic liquid;

wherein the aqueous phase is a dispersed phase of distinct particles in the oil phase and comprises water and 15-20% based on the weight of the water-in-oil emulsion of a water soluble polymer comprising (meth)acrylamide and (meth)acrylic acid; and

wherein the surfactants comprises a tall oil fatty acid diethanol amine, a polyoxyethylene (5) sorbitan monooleate, and a sorbitan monooleate;

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.

15. The method according to claim 14 , wherein the water soluble polymer is a polymer formed by polymerizing a monomer mixture comprising about 60% to about 99% by weight acrylamide and about 1% to about 40% by weight acrylic acid or its corresponding salts.

16. The method according to claim 14 , 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 its corresponding salts after being polymerized.

17. The method according to of claim 14 , 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.

18. The method according to claim 14 , 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 according to claim 14 , 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 acrylamide is present in the water soluble polymer in an amount in the range of from about 60% to about 80% by weight of the polymer.

20. The method according to claim 14 , 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).