Polysaccharide Treatment Fluid and Method of Treating a Subterranean Formation

A method of treating a subterranean formation penetrated by a wellbore, the method comprising:

• providing a treatment fluid comprising an aqueous medium, a polymeric viscosifier, a peroxide breaker, a breaking aid or catalyst;
• and an iron contamination control agent;
• and,
• introducing the treatment fluid into the formation through the wellbore.

A method of cleaning a wellbore 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;
• R1, R2, R3, R4, R5, R6, R7, R8, R9, and R10 are selected from the group consisting of hydrogen, methyl, acetyl, glyceryl, or a saccharide group containing one to three saccharides units;
• R11 is a methyl or methylol group;
• and the weight average molecular weight (Mw) for the heteropolysaccharide is from about 105 to about 107;
• and
• a diutan reactive peroxide breaker;
• a breaking aid or catalyst;
• and,
• an iron contamination control agent;
• providing a coiled tubing apparatus which further comprises a plurality of cleaning nozzles;
• introducing the coiled tubing apparatus into the wellbore;
• introducing the treatment fluid into the wellbore through the coiled tubing to enable mixing of the treatment fluid and wellbore solids;
• and,
• subsequently allowing the peroxide to effectively decrease the viscosity of the mixture of the treatment fluid and the wellbore solids;