Universal perforating gun firing head

An improved firing head for actuating an explosive charge in a perforating gun positioned downhole in a well, comprising:

• a hollow housing for containing a fluid pressurized from the well surface;
• a firing pin within said housing for impacting the explosive charge;
• a first retainer for securing said firing pin;
• a release pin engaged with said retainer for securing said firing pin, wherein movement of said release pin releases said retainer to permit said firing pin to contact the explosive charge;
• a differential piston within said housing which is moveable in response to changes in the fluid pressure within said housing;
• a port in said housing for communicating the well pressure to said differential piston;
• and
• a second retainer for releasably engaging said differential piston and said release pin, wherein said second retainer attaches said release pin to said differential piston to release said first retainer when said differential piston is moved by the fluid pressure changes, and wherein said second retainer disengages said release pin from engagement with said differential piston when said release pin is mechanically actuated.

An improved firing head for actuating an explosive charge in a perforating gun positioned downhole in a well, comprising:

• a hollow housing for containing a fluid pressurized from the well surface;
• a firing pin within said housing for impacting the explosive charge;
• a first retainer for securing said firing pin;
• a release pin engaged with said retainer for securing said firing pin, wherein movement of said release pin releases said retainer to permit said firing pin to be forced by the pressurized fluid into contact with the explosive charge;
• a differential piston within said housing and concentrically positioned about said release pin, wherein said differential piston is movable in response to changes in the fluid pressure within the housing;
• a port in said housing for communicating the well pressure to said differential piston, and
• a second retainer for releasably engaging said differential piston and said release pin, wherein said second retainer attaches said release pin to said diferential piston to release said first retainer when said said differential piston is moved by the fluid pressure changes, and wherein said second retainer disengages said release pin from engagement with said differential piston when said release pin is mechanically actuated.