DEVICES FOR ACTUATING EXPLOSIVE CHARGES IN WELLBORES, AND METHODS OF PERFORATING BOREHOLES

摘要

A device (10) for actuating an explosive charge downhole in a wellbore includes a combustive reaction initiator (30, 66, 100) actuated in response to a first pressure condition in a portion of the wellbore and an explosive charge actuator. A time delay device (136) is provided wherein a combustive reaction is initiated by the initiator and continues for a time delay period providing sufficient time for an operator to alter the first pressure condition to a second pressure condition at the time of explosive actuation. The delay device is operative at the end of the time delay period after initiation to actuate the explosive charge.