A system and method to control wellbore pressure during perforating. The system comprises a carrier, a sensor, a pressure-altering device, and a processor in communication with the sensor. The sensor is configured to detect a stress wave propagating through the carrier before the arrival of a related pressure wave in the wellbore and generate a signal indicative of the detected stress wave. The pressure-altering device is actuatable to change the pressure in the wellbore. The processor is operable to analyze the signal from the sensor and control the pressure-altering device based on the detected stress wave to change the magnitude of the related pressure wave in the wellbore.

A system, method, and device for monitoring a parameter downhole. The system comprises a conveyance string locatable in the wellbore, a sensor and a recorder located on the conveyance string, and a processor in communication with the recorder. The recorder comprises a sampler in communication with the sensor, and the sampler is operable to sample the measured parameter at a sampling rate of 150 kHz to 10 MHz. The recorder also comprises an information storage device in communication with the sampler and operable to store the samples acquired by the sampler. The processor is operable to monitor the parameter based on the samples collected by the sampler.

A method and apparatus according to which a perforating gun includes a first detonation train and a second detonation train. The first detonation train is detonable to perforate a wellbore proximate a subterranean formation. The first detonation train includes a first detonating fuse and a perforating charge ballistically connected to the first detonating fuse. The second detonation train is detonable to increase an internal energy of the perforating gun after detonation of at least a portion of the first detonation train. The second detonation train includes a second detonating fuse ballistically connected to the first detonating fuse. In some embodiments, increasing the internal energy of the perforating gun after detonating the at least a portion of the first detonation train decreases and/or delays pressure drawdown within the wellbore.

A perforating gun and method according to which a perforating charge of the perforating gun is detonated. Detonating the perforating charge produces shock waves. In some embodiments, detonating the perforating charge also perforates a wellbore proximate a subterranean formation. After detonating the perforating charge, first and second components of a binary energetic of the perforating gun are fragmented by the shock waves, mixed by the shock waves, and activated by the shock waves to increase an internal energy of the perforating gun. In some embodiments, increasing the internal energy of the perforating gun after detonating the perforating charge delays and/or decreases wellbore pressure drawdown.

Provided are compositions, methods, and systems that relate to use of viscoelastic surfactant gels in well perforation. A method for well treatment comprising: introducing a viscoelastic surfactant gel into a wellbore; and forming one or more perforation channels in an interval of the wellbore while the viscoelastic surfactant gel is disposed in the wellbore. A method for well treatment comprising: introducing a viscoelastic surfactant gel into a wellbore over an interval of the wellbore to be perforated; disposing a perforating gun into the wellbore such that the viscoelastic surfactant gel is disposed between the perforating gun and a casing of the wellbore; and forming one or more perforation channels in the interval of the wellbore. A downhole perforating system comprising: a perforating gun disposed at a distal end of a work string; and a viscoelastic surfactant gel.

A re-fracturing method using a perforating gun system in a multistring wellbore casing with an inner well casing installed in an outer well casing. The charges in the perforating system include a case, a liner positioned within the case, and an explosive filled within the liner. The liner shaped with a subtended angle about an apex of the liner such that a jet formed with the explosive creates an entrance hole in the inner well casing and the outer well casing; the liner having an exterior surface, the exterior surface substantially conical proximate the apex; the subtended angle of the liner ranges from 100 to 120. The method includes covering the existing openings with the inner casing, perforating with the perforating system and creating constant diameter entrance holes in the outer casing and fracturing through the inner casing and outer casing.

The invention relates to the field of oil and gas production. A perforating gun comprises a single-piece housing containing cavities perpendicular to its longitudinal axis, said cavities being formed directly in the material of the housing of the perforating gun. The following individually manufactured, conjoined structural parts of a shaped charge are hermetically installed directly in the cavities: an outer cap of the shaped charge; a hermetic seal in the form of a ring or gasket; a charge cavity; and a primary explosive pellet. Also disposed in the housing are: a detonation transmission amplifier; a sealing ring a detonating cord; and a plug with a groove. A detonating cord is connected to each charge, said detonating cord being disposed in a channel formed along the outer surface of the housing and being balistically connected via an opening to the pellet in the cavity.

An apparatus and method according to which a perforating gun includes a volume fill body. The volume fill body is positioned in the space between a charge tube and a carrier tube. The fill body occupies at least part, and sometimes all, of the free volume space between the charge tube and carrier tube thereby reducing the free volume space. In certain downhole applications, large free volume space can lead to significant reductions in wellbore pressure, causing dynamic underbalance, which is undesirable. The presence of the volume fill body prevents, or at least reduces, dynamic underbalance and its effects. Also, the volume fill body aligns the charge tube with the carrier tube, further assisting perforation.

A system and method to control wellbore pressure during perforating. The system comprises a carrier, a sensor, a pressure-altering device, and a processor in communication with the sensor. The sensor is configured to detect a stress wave propagating through the carrier before the arrival of a related pressure wave in the wellbore and generate a signal indicative of the detected stress wave. The pressure-altering device is actuatable to change the pressure in the wellbore. The processor is operable to analyze the signal from the sensor and control the pressure-altering device based on the detected stress wave to change the magnitude of the related pressure wave in the wellbore.

A technique facilitates mitigation of shock loads. Subterranean communication systems may comprise components susceptible to various shock loads. A shock mitigation system is physically coupled with the subterranean communication system to mitigate such shock loads. The shock mitigation system comprises components selected to enable reduction of various effects of shock loads, e.g. shock loads resulting from perforating procedures, which could otherwise be detrimental to continued operation of the subterranean communication system.