Patent ID: 9476290
Filing Date: 2016-10-25
CPC Classification: E21B

Claim Text:
1. A system for detonating explosive materials in a down hole well tool, said system comprising: a down hole well tool having explosive materials therein; a firing head secured to said well tool for detonating said explosive materials, said firing head having a fluid pressure displaced firing pin aligned to impact an explosive detonator; a piston sub secured to said firing head having an axial bore within a cylinder wall, said bore extended between a distal end of said bore and a firing head end; a first aperture through said cylinder wall to admit well fluids into said bore a piston within said bore proximate of said bore distal end; a resilient bias on said piston urging said piston toward said bore distal end; an extension from said piston projected axially past said bore distal end for engaging a well bore obstacle to displace said piston against said resilient bias and pressure well fluids in said bore to displace said firing pin.