Patent ID: 7536942
Filing Date: 2009-05-26
Classification: E21B,F42B,F42D

Abstract:
1. A method of severing a string of pipe extending within a well bore from a wellhead site, said method comprising the steps of: at a first location distal from a well bore, partially assembling a severing tool comprising an internal barrel space having opposite distal ends, at least one of said distal ends formed by a selectively removed end closure, electrically actuated detonators positioned on said end closure and at the other distal end of said barrel space, said detonators being connected to ignition signal conductors; transporting said partially assembled severing tool with said connected detonators to a second location proximate of a well bore, said barrel space being substantially devoid of explosive material between said detonators during such transport; at said second location, removing said end closure without interrupting said ignition conductor connection and placing into said barrel space a column of explosive material of sufficient quantity to sever a pipe within said string; replacing said end closure to engage said column of explosive material at opposite distal ends by said detonators and to close said barrel space; positioning said severing tool at a predetermined location within a string of pipe suspended within said well bore; and, detonating said column of explosive material substantially simultaneously at opposite distal ends by an electrical signal to said ignition signal conductors to sever said pipe string.