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.

An active energy-absorbing shock absorber for perforation combined well testing includes a first energy-absorbing mechanism, a second energy-absorbing mechanism and an axial-force cushioning mechanism. The first energy-absorbing mechanism includes a gun body, a gun head, a gun tail joint, a support frame, an energy-absorbing filling layer and a detonation mechanism. The second energy-absorbing mechanism includes an intermediate connecting cylinder, an outer cylinder, a limiting step, a movable impact head, a support base, a hydraulic buffer mechanism, a piston rod, an energy-absorbing spring and an inner cavity piston. The axial-force cushioning mechanism includes a housing, a guide mechanism, a buffer shaft and a multi-stage buffer spring. The absorber with a multi-layer structure is filled with a foam aluminum material.

An apparatus for dampening vibrations in a drill string has a tubular housing with an upper sub connected to a first end, having a threaded connection for engagement with the pipe or drillstring. A piston is positioned in the bore of the tubular housing and longitudinally movable in the bore; the dimensions of the piston and bore permit limited fluid flow around the piston. Connected to the piston and extending out of the second end of the housing is a bottom sub. Mating and engaging profiles in the tubular housing and lower sub allow longitudinal movement between them, but no relative rotation. A spring member, which may be a mechanical spring, an elastomeric member, a compressed gas, or some combination thereof, biases the piston and lower sub out of the tubular housing.

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 includes 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.

In an embodiment, a sensing subassembly for use with a downhole tool comprises a housing, a cavity extending into the housing, a sensor disposed at least partially within the cavity, a shock mitigating member disposed between at least one end of the sensor and the housing, and at least one seal member disposed between the sensor and the housing. At least a portion of the sensor is in fluid communication with an exterior of the housing, and the shock mitigating member is configured to attenuate at least a portion of a shock wave between the housing and the sensor.

The embodiments described herein generally relate to a fluid pressure pulse generating apparatus with a primary seal assembly, back up seal assembly and pressure compensation device. The pressure compensation device comprises a membrane support and a longitudinally extending membrane system. The membrane support has a longitudinally extending bore therethrough for receiving a driveshaft of the fluid pressure pulse generating apparatus. The longitudinally extending membrane system comprising a longitudinally extending outer membrane sleeve and a longitudinally extending inner membrane sleeve with the inner membrane sleeve positioned inside the outer membrane sleeve. The membrane system is sealed to the membrane support to allow flexing of the membrane system in response to fluid pressure on either an inner longitudinal surface of the membrane system or an outer longitudinal surface of the membrane system and to prevent fluid on the inner longitudinal surface mixing with fluid on the outer longitudinal surface.

A sensing subassembly for use with a downhole tool comprises a housing, a cavity disposed within the housing, an electronic board disposed within the cavity, a stiffening member engaging the electronic board and configured to limit flexing of the electronic board, and a spring member configured to provide an isolation mount for the electronic board within the cavity.

A single-trip method and system for perforating casing allows displacement of a heavier completion fluid from the perforation zone by a lighter formation-compatible treatment fluid without the need for an extended rat hole or repositioning the working string. The perforating system includes bridge subs located above and below a perforating gun. The bridge subs bypass treatment fluid around the gun through one or more conduits located along the exterior of the gun into a discharge flow port located immediately below the lower bridge sub. The system may be hydrodynamically designed to maintain efficient fluid displacement characteristics of the discharge flow port. The external conduits are positioned to not interfere with perforation operations and may include parallel conjoined tubes. The perforating system may be lowered to a perforation position in the wellbore, and treatment fluid pumped through the discharge flow port to displace completion fluid prior to perforation operations.

A method and system for preparing or treating a wellbore in conjunction with a perforating operation. The disclosed perforating gun system includes one or more perforating guns between an uphole flow sub and a downhole flow sub. The uphole flow sub and the downhole flow sub are connected by a fluid bypass that permits fluid to be pumped into the wellbore below the perforating guns. Before perforation, formation-compatible fluid may be pumped through the first and second flow subs via the fluid bypass to displace fluid and debris that may interfere with or cause unwanted damage during perforation. Alternatively, the fluid may be a treating fluid selected to dissolve debris within the wellbore. Following perforation, the fluid may be circulated through the wellbore to remove or dissolve debris created during the perforating process.

An assembly with a shock inducing tool and shock sensitive components. The assembly includes a shock mitigator that is constructed in a manner that allows a communication line to stretch across an interface of the mitigator between a housing for the components and the shock inducing tool. So, for example, where the tool is a perforating gun, power and/or communication with the tool need not be sacrificed for in exchange for safeguarding electronic components of the housing with the mitigator.