Patent ID: 8367589

Claim:
A method of treating a subterranean formation penetrated by a wellbore, the method comprising: providing a treatment fluid comprising: an aqueous medium; a diutan heteropolysaccharide having a tetrasaccharide repeating unit in the polymer backbone as represented by the formula: wherein at least three different saccharides are present in the repeating unit, such saccharides including D-glucose, D-glucuronic acid, and either L-rhamnose or L-mannose; M + is an ionic species; R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 , and R 10 are selected from the group consisting of hydrogen, methyl, acetyl, glyceryl, or a saccharide group containing one to three saccharides units; R 11 is a methyl or methylol group; and the weight average molecular weight (Mw) for the heteropolysaccharide is from about 10 5 to about 10 7 ; a peroxide breaker selected from the group consisting of urea peroxide, sodium percarbonate, potassium percarbonate, ammonium percarbonate, sodium perborate, hydrogen peroxide, a surfactant-stabilized peroxide, an encapsulated peroxide and combinations thereof; and a breaking aid or catalyst selected from the group consisting of iron (II) sulfate and hydrates thereof, iron (II) chloride, iron (II) gluconate, iron powder with a pH-adjusting agent, and combinations thereof; and, introducing the treatment fluid into the formation through the wellbore.