| 摘要 |
A method and apparatus for effecting the firing of a perforating gun having a plurality of vertically spaced, shaped charges wherein the firing is accomplished from the lowermost shaped charge to the uppermost shaped charge. In one modification, the detonation of the shaped charges is accomplished by a primer cord extending through all the gun sections, which is detonated only by a booster charge located in the bottom portion of the perforating gun housing. The booster charge is in fluid communication with the interior of the housing and, upon the occurrence of leakage of well fluids into the housing, the booster charge is rendered ineffective, thus preventing the firing of the perforating gun when the lower portion of the gun is filled with well fluids. In another modification, a conventional primer cord with booster charges on each end is inserted in each gun section, as is a length of flame-transmitting tubing. A flame is conveyed by such tubing from the top of the gun to the bottom to ignite a booster charge which causes the detonation of the primer cord in the bottom section, which detonation moves upwardly through all the gun sections.
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