Apparatus for arming, testing, and sequentially firing a plurality of

Abstract

A perforating gun apparatus comprises a plurality of perforating gun, each gun containing at least one charge and a novel arming, testing and firing apparatus. The arming, testing and firing apparatus arms a first charge in a lowermost perforating gun; however, the arming of the first charge in the lowermost perforating gun allows a tester disposed at the well surface to determine the identity of the lowermost perforating gun to be detonated. Furthermore, the arming of the first charge in the lowermost perforating gun also enables the arming of a second charge in an adjacent perforating gun of the gun string. In the event the first charge is not armed as expected, the arming, testing and firing apparatus in the lowermost perforating gun bypasses the lowermost perforating gun and begins to arm the second charge in the adjacent perforating gun of the gun string. A novel housing for a perforating gun includes an isolated chamber in which a charge is mounted, the chamber having two opposite walls, one wall being circumferentially rotatable and including a radially disposed detonator. Since a detonating cord is longitudinally disposed in the chamber, the circumferentially rotatable characteristic of the one wall in association with the radial disposition of the detonator provides a safe arm feature of the perforating gun.