Patent ID: 9540913
Date: 2017-01-10
CPC Classifications: E21B

Claim:
1. A method of actuating a differential pressure firing head to actuate a perforating gun at a downhole location in a subterranean wellbore adjacent a formation, the method comprising: positioning the perforating gun and the differential pressure firing head at a downhole location on a tubing string; communicating an applied fluid pressure to a wellbore annulus, a first chamber, and a sealed second fluid chamber, wherein the wellbore annulus is defined between the perforating gun and firing head and the wellbore, wherein the first chamber communicates the applied fluid pressure to a low-pressure side of the firing head, and wherein the sealed second fluid chamber communicates the applied fluid pressure to a high-pressure side of the firing head; trapping the applied fluid pressure within the second fluid chamber; and decreasing the applied pressure in the first chamber and the wellbore annulus, thereby creating a differential pressure across the firing head sufficient to actuate the firing head.