Novel Electro-Hydraulic Intelligent Firing Head for Tubing Conveyed Perforating

Abstract

Existing pressure-sensitive firing heads are either hydraulic or electronic. Hydraulic firing heads have the advantage of simplicity and cost. In addition, hydraulic firing heads do not have batteries and can, therefore, remain downhole for several months before functioning. This enables the operator to utilize their assets and equipment more economically. Electronic firing heads, however, enable operations in small pressure margin wells and allow for more advanced completion equipment and services. The newly-developed electro-hydraulic firing head combines the long downhole life of a hydraulic firing head with the capabilities of an electronic firing head. An electronic module is programmed at surface to respond only to a pre-programmed pressure signature. Upon detecting this signature, the electronic module activates the hydraulic firing mechanism, initiating the perforating guns below. This hybrid design incorporates safety features that were previously unique to each type of firing head. The hydraulic firing mechanism, which uses a percussion detonator, eliminates the need for electronic detonators that are sensitive to electro-magnetic interference (EMI) caused by rigsite communications devices. Additionally, this mechanism must have several thousand PSI to function, making surface detonation impossible. The electronics module prevents the firing head from functioning from an unintended overpressure of the wellbore, greatly reducing the possibility of firing off-depth. This paper will discuss the design, development, and testing of this firing head from a mechanical and electrical engineering point of view, as well as the operational reliability, safety, and human interface features included in the design. In addition, it will discuss the test plan to qualify the tool for reliable and safe operations at up to 30,000 psi at 400ºF, as well as the test results.