Percussion operated firing mechanism for perforation of wellbores and methods of using same

摘要

Perforation guns comprise a firing head to activate an initiator which, in turn, causes detonation of perforation charges. The firing head comprises a firing pin in sliding engagement with a bore of a housing. An opening in the housing places the firing pin in fluid communication with a wellbore annulus when the perforation gun is disposed in the wellbore. A release mechanism maintains the firing pin in it is initial position. Upon being disposed in the desired location within the wellbore, the release mechanism is actuated allowing the firing pin to move within the bore. Hydrostatic pressure acts on the firing pin in a first direction that is determined by a bias provided by one end of the firing pin providing greater resistance to movement as compared to the other end. Movement of the firing pin causes the firing pin to strike the initiator causing detonation of the perforation charges.

主权项

1. A firing mechanism for a downhole perforation gun, the firing mechanism comprising:
a tubular member having an upper end, a lower end, an outer wall surface, and an inner wall surface defining a bore; an opening disposed in the inner and outer wall surfaces and in fluid communication with the bore; an initiator disposed at the lower end of the tubular member, the initiator being operatively associated with a perforation charge; a firing pin disposed within the bore, the firing pin comprising an initial position, a firing position, a shaft having a firing pin lower end, a lower middle portion, a lower end portion, a first lower gap, and a second lower gap, the lower middle portion and lower end portion being in sliding engagement with the inner wall surface, the first lower gap being disposed between the lower portion and the lower middle portion and the second lower gap being disposed between the lower middle portion and the lower end portion, a firing pin upper end, a lower portion in sliding engagement with the inner wall surface of the tubular member, the lower portion having an upper surface in fluid communication with the opening, the firing pin having a bias of movement from the initial position to the firing position; and a release mechanism operatively associated with the firing pin, the release mechanism maintaining the firing pin in the initial position until actuated, wherein actuation of the release mechanism frees the firing pin to slide along the inner wall surface of the tubular member toward the firing position at which the initiator is activated by the firing pin contacting the initiator.