Pressure Activated Selective Perforating Switch Support

Abstract

A method, system, and apparatus for restraining a firing pin using a bushing for use in a downhole switch that is armed using the explosive energy of a previously detonated shaped charge.

What is claimed is: 
     
         1 . A method for detonating a shaped charge comprising:
 assembling at least one perforating gun to at least one tandem sub;   installing at least one perforating shaped charge in the at least one perforating gun;   installing at least at least one detonator in the at least one tandem sub;   installing a detonating cord between the detonator and the at least one shaped charge;   installing a switch in the tandem sub;   assembling an arming switch for a downhole perforating gun with a firing piston having a distal end protruding from the switch;   machining a groove on a distal end of the piston;   engaging a support busing on the distal end of the piston, wherein the support bushing is located between the switch housing and the machined groove; and   installing a retaining device on the machined groove, wherein the retaining device engages with the support bushing.   
     
     
         2 . The method of  claim 1  further comprising detonating a second shaped charge, wherein the detonation activates the switch and arms the at least one detonator. 
     
     
         3 . The method of  claim 1  further comprising electrically activating the at least one detonator.