Pressure activated well perforating technique.

摘要

A well perforating technique utilizes a predetermined pressure difference developed at different points in the borehole to actuate the firing mechanism of a tubing conveyed perforating gun. A first embodiment incorporated as part of a well test string includes a packer for isolating a wellbore interval and a perforating gun connected in the string below the packer which is fired in response to development of a greater pressure in the annulus above the packer than in the isolated interval, thereby causing perforation at «underbalanced» conditions. A modified «full-bore» embodiment has an annular configuration firing mechanism as part of a tubing string and fires the perforating gun in response to development of a predetermined difference between the pressures at a point in the annulus and a point in the central bore of the tubing string.