In general, in one aspect, embodiments relate to a perforating gun that includes a gun body, a charge tube disposed within the gun body, a plurality of charge cases disposed within the charge tube, and a sacrificial fill material disposed within at least a substantial portion of an inner cavity of the charge tube.

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.

Provided is a vibration-damping sub, a tool string, and a method. The vibration-damping sub, in one aspect, includes a tubular damping body having a tubing wall defining a longitudinal axis and opposing ends for connecting the tubular damping body within a tool string between a vibration source and a vibration-sensitive tool. The vibration-damping sub, according to this aspect, may further include a plurality of shaped holes extending through the tubing wall and configured to impede propagation of mechanical waves along the tubular damping body, wherein each of the plurality of shaped holes extends through the tubing wall at an angle () of at least 5 degrees relative to perpendicular to the longitudinal axis of the tubular damping body for redirecting the mechanical waves.

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 7 aluminum material.

In general, in one aspect, embodiments relate to a perforating gun that includes a gun body, a charge tube disposed within the gun body, a plurality of charge cases disposed within the charge tube, and a sacrificial fill material disposed within at least a substantial portion of an inner cavity of the charge tube.