Methods of perforation using viscoelastic surfactant fluids and associated compositions

Abstract

The invention provides a method for perforating a well with a perforating fluid comprising a viscoelastic surfactant that essentially stops fluid leak-off after perforation in an overbalanced condition. Another aspect of the invention provides the perforating fluid in itself. The well has a wellbore defined by a generally cylindrical casing in at least a portion of the wellbore (i.e., the wellbore is cased, although it is not necessary cased in its entire length). The wellbore passes through a subterranean formation that comprises hydrocarbon formation fluids (such as oil and/or gas), at least in certain strata. The method comprises placing a perforating device in a wellbore which includes at least one explosive perforating charge that can be detonated in order to perforate the casing and allow the formation fluids to enter the wellbore. The casing is located between the subterranean formation and the perforating device. A perforating fluid including at least one viscoelastic surfactant is placed in the wellbore between the perforating device and the casing, in at least a portion of the wellbore. In other words, the perforating fluid is present in the wellbore adjacent to the perforating device. The explosive charge(s) in the perforating device is detonated, such that the perforating device forms at least one perforation in the casing that permits the flow of hydrocarbon formation fluids from the subterranean formation into the wellbore. As a result of the detonation, at least a portion of the perforating fluid is put in communication with the subterranean formation.