Bottom hole firing head and method

摘要

Detonation of a perforating gun is initiated by engagement of the lower distal end of the gun assembly against a bottom hole bore plug. A fluid pressure actuated firing head is initiated by well fluid that is pressurized by a free piston having an integral rod projecting from the distal end of the gun assembly. The piston is displaced against a closed fluid volume when the projecting rod engages the bore plug.

主权项

1. An explosive detonation sub for detonating explosive well tools, said sub comprising:
a cylindrical housing having an axially open fluid path between a detonator end and a piston end including a piston bore; an axially translated piston within said piston bore that is resiliently biased toward a distal end of said piston bore; a percussion detonator proximate of said detonator end; a firing pin displaced by a fluid pressure pulse in said fluid path for detonating said detonator; and a piston rod projected from a piston end of said housing for displacing said piston to generate a fluid pressure pulse in said fluid path; and, a first aperture through a housing wall into said piston bore to vent a predetermined volume of fluid upon displacement of said piston prior to generation of said pressure pulse.