Patent ID: 8871691

Claim:
A method of treating flowback water from a subterranean formation penetrated by a well bore, comprising: (1) providing flowback water having a ferrous iron (Fe +2 ) ion concentration of less than about 100 milligrams of ferrous iron ion per liter of flowback water, a barium ion (Ba +2 ) concentration of less than about 500 milligrams of barium ion per liter of flowback water, and a calcium ion (Ca + ) concentration of at least about 1,000 milligrams of calcium ion per liter of flowback water; (2) treating the flowback water with a fluid treatment system comprising: (a) at least one friction reducing agent comprising a water-in-oil emulsion composition comprising: 5% to 99% by weight of a water-in-oil emulsion polymer comprising at least one polyacrylamide comprising one or more repeat units according to Formula I: wherein each occurrence of R 1 is independently selected from H, methyl and ethyl; n is an integer from 10 to 10,000,000; Z is selected from —O—and —NR 2 —; and each occurrence of R 2 is independently selected from the group consisting of H, C 1 -C 22 linear, branched or cyclic alkyl, aryl, alkaryl, aralkyl or alkenyl group,—R 3 —NR 2 2 ,—R 3 —N + R 2 3 X, and —R 3 —SO 3 Y, wherein R 2 is as previously defined; R 3 is a divalent linking group selected from the group consisting of C 1 -C 22 linear, branched or cyclic alkylene, arylene, alkarylene, aralkylene or alkenylene, poly(ethyleneoxide) and poly(propyleneoxide); Y is H or an alkali metal ion; and X is a halide or methylsulfate, wherein the polyacrylamide has a molecular weight of 1,000,000 to 50,000,000 grams per mole; (ii) 0.1% to 10% by weight of one or more inorganic microparticles; (iii) 0.5% to 90% by weight of a carrier solvent; and (iv) 0 to 90% by weight of a fluidizing agent; (b) at least one scale formation inhibiting agent selected from the group consisting of water-soluble polycarboxylates, phosphonates, metal salts, sulfonates, and mixtures thereof, and (c) at least one iron control agent comprising (1) at least one carboxylic acid functional group and (2) at least one sulfur-containing group selected from the group consisting of sulfonyl functional groups, sulfonate functional groups, and mixtures thereof, wherein the material (a) has a weight average molecular weight ranging from about 500 to about 30,000 grams per mole, to provide treated flowback water; and (3) introducing the treated flowback water into a subterranean formation as an aqueous fracturing fluid for hydraulic fracturing of the formation.