Patent ID: 8205675
Filing Date: 2012-06-26
Classification: C09K,E21B

Abstract:
1. A method of hydraulically fracturing a subterranean formation comprising: (a) pumping into the formation at least two stages wherein a first stage is a proppant-free fluid and a second stage is a proppant laden slurry and further wherein one of the stages contains at least one member selected from the group consisting of viscosifying polymers and viscoelastic surfactants; and the other stage contains a breaker and optionally a viscosifying polymer, viscoelastic surfactant and/or friction reduction agent; and (b) degrading the viscosifying polymer or viscoelastic surfactant of the stage containing said at least one member with the breaker of the other stage wherein the breaker has greater affinity for the viscosifying polymer or viscoelastic surfactant of said at least one member than the optional viscosifying polymer, viscoelastic surfactant and/or friction reduction agent which may be present in the stage containing the breaker.