Patent ID: 8158562

Claim:
A fracturing fluid comprising: a hydratable polymer, a cross-linking amount of a cross-linking composition comprising one polyvalent metal salt or a plurality of polyvalent metal salt and a phosphate ester cross-linking agent, where the metal or metals of the salt or salts are selected from the group consisting of titanium, chromium, iron, aluminum, and zirconium and where the phosphate ester cross-linking agent is selected from the group consisting of alkali, alkaline earth metal, or transition metal salts of alkyl phosphate esters, alkoxy phosphate esters, glycols phosphate esters, alkypolyol phosphate esters and mixture or combinations thereof; and a delaying amount of a cross-linking retarding composition consists essentially of a polyhydroxy or polyol compound in an amount of 20 wt. % up to 30 wt. % based on the cross-linking composition, where the phosphate ester increases a rate of crosslinking to seconds, and where the cross-linking amount is sufficient to result in a desired viscosity increase in the fluid and the retarding amount is sufficient to delay the cross-linking for a desired period of time measured in minutes.