Patent ID: 6053111
Filing Date: 2000-04-25
Classification: E21B,F42B,F42D

Abstract:
An explosive device for use in a subterranean well, the well extending from the surface of the earth to a downhole portion in which the explosive device is to be used, the downhole portion being at a higher temperature than the surface, the explosive device comprising:an explosive;an electrically conductive capable of supplying electricity that can fire the explosive; and,a thermal switch electrically connected in the circuit, the thermal switch capable of multiple cycling between an open position and a closed position as the temperature of the thermal switch is changed from the temperature on the surface to the temperature in the downhole portion, the thermal switch being set such that the thermal switch is open at the surface temperature and closed at the downhole temperature, thereby permitting the explosive to be electrically fired when the switch is at the downhole temperature.