Firing heads are a widely used term for the initiation device of perforating gun systems and other pyrotechnical devices deployed on wireline and tubing-conveyed perforating (TCP) operations. The perforating systems have improved dramatically since the first successful commercial TCP job was performed in 1970 using a mechanically initiating firing head. Over the last several decades, the technological development of the TCP firing systems have rendered perforating systems more robust, safer, and operationally flexible.

Recently, perforating firing heads have been mainly designed on the basis of hydraulic and mechanical operation, which typically requires the shearing of pins through pressure activation or use a drop bar to create mechanical impact. Features, such as firing delay or multiple pressure-cycle operation, have been developed, with additional complexity. Such mechanical systems are not always precise in operation due to tolerances and can be influenced by variations in downhole conditions, such as temperature, pressure, and duration.

The electronic firing heads introduced over two decades ago provided immunity to variations of downhole conditions, offered improved accuracy and control, and eliminated the need for high-pressure pulses normally required to activate a hydraulic firing head. Communication relied upon a coded low-pressure command sequence of pulses. This introduced a safer, more efficient, and economical method for a wide range of downhole explosive operations.

The most recent advancements in the electronic firing head have been enabled by wireless acoustic telemetry. This evolution step provides a perforating firing head combinable with drill stem testing assemblies. The wireless technology-enabled electronic firing head is the integration of two proven technologies: the electronic intelligent low-pressure firing head and the wireless acoustic telemetry system. The electronic firing head enabled by wireless acoustic telemetry system allows multizone drill stem testing (DST), independently or selectively with comingled reservoir, providing the ability to initiate guns where pressure activation is not possible.

We describe the evolution of the firing system and operation of this newly developed and advanced acoustically actuated electronic firing head. Two case studies summarize the benefits and capabilities of the firing head enabled by the wireless acoustic telemetry system.