Firing trigger apparatus and method for downhole tools

Abstract

Methods and devices are provided for controlling detonation of explosives in a well bore for perforation or a well bore casing, which avoid or reduce unintentional or undesirable detonations while ensuring or increasing desirable detonations. An explosive trigger system or tool may comprise a central processing unit (CPU), memory, and one or more sensors disposed for measuring one or more downhole conditions. Downhole conditions may be measured with the sensor and then used to program detonation parameters (such as temperature or pressure) or preconditions (such as time or distance traveled) to the trigger system. Detonation can only occur when the programmed parameters or preconditions are satisfied. In this way, undesirable detonations are avoided by requiring certain preconditions to arming the trigger system. To further control arming and/or detonating, a line sequencer may be provided, wherein energy is propagate down along the physical deployment line as pulses or line 'jerks' through mechanical manipulations of physical deployment line near surface. These pulses can form signals for downhole control of the trigger system.