METHODS OF FRACTURING A SUBTERRANEAN FORMATION USING A PH DEPENDENT FOAMED FRACTURING FLUID

摘要

Methods of fi-acturing a subterranean formation include providing a ftacturing fluid having a first pH. The fracturing fluid may be made by combining a gelling agent, a surfactant, and a proppant. The surfactant is capable of facilitating foaming of the fracturing fluid at the first pH and defoarning of the fi-acturing fluid when its pH is changed to a second pH. The methods of fracturing the subterranean formation further include foaming the fracturing fluid having the first pH and subsequently purnping it to the subterranean formation to fracture the formation. The pH of the fracturing fluid changes to a second pH, for example via in situ contact with an acidic material, causing the level of foam in the fracturing fluid to be reduced. As a result of the reduction of the foam, the fracturing fluid deposits the proppant into the fractures formed in the subterranean formation.