US Patent 8003577 Method of treating subterranean formation with crosslinked polymer fluid

A method of treating a subterranean formation penetrated by a wellbore utilizes a treating fluid formed from an aqueous solution of a water-soluble polymer. The treating fluid further contains a crosslinking agent and an optional delayed release alkaline additive. The delayed release alkaline additive may be at least one of urea, a urea derivative, a solid alkaline earth metal carbonate, a solid alkaline earth metal oxide and combinations of these. The treating fluid further includes an acidic pH adjusting agent used in an amount to provide the treating fluid with a pH of less than about 5. The treating fluid is then introduced into the formation.