HEAT ACTIVATED BALLISTIC BLOCKER

摘要

A method and an apparatus for use in a wellbore are provided to prevent an igniter (78) from igniting a pyrotechnic device (80) within a downhole well tool until after the downhole well tool is positioned downhole within the wellbore. A blocking member (104) is movable between two positions for selectively obstructing an ignition pathway between the igniter (78) and pyrotechnic device (80). An actuator (108) is provided which, when heated to an activation temperature by downhole well temperatures, moves the blocking member (104) from a position obstructing the ignition pathway to a position for allowing the igniter to ignite the pyrotechnic device.