Perforating gun drop sub

摘要

A perforating gun assembly comprises a drop sub linking the firing head to the gun tube or tubes. The drop sub includes a 360° perimeter shaped charge explosive for severing pipe having an axial bore to accommodate a pass-through of the perforation charge detonation chord. Consequently, the severing tool is detonated by the traverse of a detonation wave along the chord length to disconnect the perforating gun prior to detonation of the perforation charges.