Abstract: A surge chamber assembly (70) for use in a wellbore includes a housing (80) having one or more openings (112), a surge chamber (100) and a combustion chamber (98). The openings (112) provide fluid communication between the exterior (82) of the housing (80) and the surge chamber (100). A sleeve (114) is slidably positioned within the housing (80) and has a first position wherein fluid communication through the openings (112) is prevented and a second position wherein fluid communication through the openings (112) is allowed. A combustible element (124) is positioned in the combustion chamber (98) such that combusting the combustible element (124) generates pressure in the combustion chamber (98) that actuates the sleeve (114) from the first position to the second position.

Abstract: A perforating safety system. A perforating safety system includes a detonation transfer interrupter with a device which decreases an axial separation between detonation transfer components after installation of the interrupter in the well. Another perforating safety system includes a perforating gun and firing head installed together in the well, and an interrupter having a device which increases a separation between detonation transfer components in the well to thereby prevent transfer of detonation from the firing head to the perforating gun. Yet another perforating safety system includes a firing head positioned at a distal end of a perforating assembly when installed in the well, and an interrupter having a device which decreases a separation between detonation transfer components after installation of the interrupter in the well.

Abstract: An explosives safety system includes an explosive component, a blocking member displaceable to selectively permit and prevent detonation of the explosive component, and a thermal actuator responsive to temperature change and configured to displace the member in response to the temperature change. Another explosives safety system includes a thermal actuator with a material having a volume variable in response to the temperature change, and detonation of the explosive component being selectively permitted and prevented by the actuator when the material volume changes.

Abstract: A surge chamber assembly (70) for use in a wellbore includes a housing (80) having one or more openings (112), a surge chamber (100) and a combustion chamber (98). The openings (112) provide fluid communication between the exterior (82) of the housing (80) and the surge chamber (100). A sleeve (114) is slidably positioned within the housing (80) and has a first position wherein fluid communication through the openings (112) is prevented and a second position wherein fluid communication through the openings (112) is allowed. A combustible element (124) is positioned in the combustion chamber (98) such that combusting the combustible element (124) generates pressure in the combustion chamber (98) that actuates the sleeve (114) from the first position to the second position.