Igniter for Downhole Use Having Flame Control

Abstract

An igniter initiates combustion in an amount of explosive that is downhole and adjacent the igniter. The igniter includes an amount of combustible material and a resistive igniter element disposed on a side of the combustible material that faces the amount of explosive. Applying a designated amount of electricity to the resistive igniter element generates sufficient heat to ignite the combustible material. Strategically initiating ignition adjacent the amount of explosive generates a flame front that travels away from the explosive, which in turn directs a flame against the explosive substantially the entire time the combustible material burns.

What is claimed is: 
     
         1 . An igniter for igniting an explosive downhole comprising:
 a housing having an opening proximate the explosive;   a pyrotechnic material in the housing;   an igniter assembly in the opening and that is in thermal contact with the pyrotechnic material, so that when the igniter element is heated to a temperature that initiates combustion of the combustible material, a flame is generated in the housing which is directed to the explosive and that ignites the explosive.   
     
     
         2 . The igniter of  claim 1 , wherein the igniter element comprises an elongated resistive element which is made from a conductive material that is heated when current flows through the resistive element. 
     
     
         3 . The igniter of  claim 2 , wherein the resistive element is mounted on a printed circuit board. 
     
     
         4 . The igniter of  claim 1 , further comprising an electrode in the housing for electrically coupling the igniter assembly with an electrical source. 
     
     
         5 . The igniter of  claim 1 , wherein the explosive is part of a perforating system. 
     
     
         6 . The igniter of  claim 1 , wherein the explosive is for setting a packer in a wellbore. 
     
     
         7 . An igniter for igniting an explosive downhole comprising:
 a housing having an opening;   a propellant in the housing;   an electrode inserted into the propellant and in electrical communication with a source of electricity;   a resistive element in electrical communication with the electrode and in thermal contact with a surface of the propellant that is proximate the explosive, so that when electricity is supplied to the electrode from the source of electricity, current flows through the resistive element and heats the resistive element to a temperature that ignites the propellant, that in turn ignites the explosive.   
     
     
         8 . The igniter of  claim 7 , wherein the resistive element comprises an elongated electrically conductive member that is arranged in a helical configuration defined by a series of loops radially spaced away from one another. 
     
     
         9 . The igniter of  claim 8 , wherein spacing between adjacent loops is greater proximate an axis of the helical configuration. 
     
     
         10 . The igniter of  claim 7 , wherein the resistive element is mounted on a printed circuit board that is set in the opening of the housing. 
     
     
         11 . The igniter of  claim 7 , wherein the explosive is selected from the list consisting of an explosive used in a perforating system and an explosive used for setting a packer. 
     
     
         12 . A method of detonating an explosive downhole comprising:
 providing an amount of combustible material in a housing adjacent the explosive;   initiating combustion of the combustible material on an end of the combustible material that is proximate the explosive so that a flame front is created in the combustible material that travels away from the explosive that in turn generates a flame that is directed from the housing to the explosive and which ignites the explosive.   
     
     
         13 . The method of  claim 12 , further comprising flowing current through a resistive element that is in thermal contact with the end of the combustible material proximate the explosive, wherein the resistive element becomes heated and initiates combustion of the combustible material. 
     
     
         14 . The method of  claim 12 , wherein the explosive is used for initiating detonation of shaped charges that create subterranean perforations. 
     
     
         15 . The method of  claim 12 , wherein the explosive is used for setting a packer in a wellbore.