Patent ID: 7036590

Claim:
A method of fracturing a subterranean zone comprising the steps of: (a) placing a first stage fluid that comprises a foamed liquid containing a water soluble gel breaker into the subterranean zone at a rate and pressure sufficient to create or extend at least one fracture therein; (b) placing a second stage fluid that comprises a viscous liquid containing proppant particles and a metal cross-linked gelling agent into the subterranean zone at a rate and pressure sufficient to cause the second stage fluid to enter the fracture; and (c) reducing the pressure in the subterranean zone so that the first stage fluid mixes with the second stage fluid and the water soluble gel breaker in the first stage fluid reacts with and uncross-links the gelling agent in the second stage fluid whereby the viscosity of the fluid mixture is reduced, the proppant particles are deposited and the fluid mixture flows out of the subterranean formation.