Methods for effecting controlled break in pH dependent foamed fracturing fluid

摘要

A fluid for use in a subterranean formation penetrated by a wellbore, the fluid comprising: (a) water; (b) an orthoester; and (c) a surfactant comprising a tertiary alkyl amine ethoxylate generally represented by the following formula: (CH₂-CH₂-O)_XH R-N<(CH₂-CH₂-O)_YH wherein R is an alkyl group or aryl group, and wherein X and Y are each independently at least one. A method of fracturing a subterranean formation, comprising the step of forming a foamed fracturing fluid comprising water; an orthoester; a surfactant comprising a tertiary alkyl amine ethoxylate generally represented by the formula above; and a gas. The method also provides the step of introducing the foamed fracturing fluid into a subterranean formation at a pressure sufficient to create a fracture in the subterranean formation.