Patent ID: 6242390
Filing Date: 2001-06-05
Classification: C09K,Y10S

Abstract:
A composition for hydraulically fracturing a subterranean formation comprising:a. an aqueous mixture of a hydrated polysaccharide, the hydrated polysaccharide having a plurality of bonding sites;b. a crosslinking agent for crosslinking the hydrated polysaccharide at the bonding sites at the conditions of the subterranean formation, with a polyvalent metal ion to form a polyvalent metal crosslink, thereby increasing the viscosity of the hydrated polysaccharide; andc. a controlled solubility compound for releasing a chelating agent for controllably breaking the polyvalent metal crosslink and bonding with the polyvalent metal ion resulting from breaking the crosslink, thereby decreasing the viscosity of the hydrated polysaccharide;wherein the controlled solubility compound is selected from the group consisting of calcium oxalate, calcium phosphate, aluminum metaphosphate, sodium zinc potassium polyphosphate glass, and sodium calcium magnesium polyphosphate glass.