Method of perforating including an automatic release apparatus suspending by wireline or coiled tubing in a wellbore for perforating a long length interval of the wellbore in a single run using a gun string longer than a wellhead lubricator

摘要

A new perforating method and release apparatus enables a wellbore operator to perforate long length intervals of a wellbore during a single perforating run into the wellbore, the interval of the wellbore being perforated being longer in length than the length of a wellhead lubricator. The new perforating method includes the step of suspending a perforating gun suing from a conveyor in a wellbore. The gun string includes a detonating cord and a novel automatic release apparatus interconnected between a first part of the gun string and a second part of the gun suing which includes a perforating gun. The automatic release apparatus includes a frangible member which will shatter in response to a detonation wave propagating in the detonating cord thereby initiating the release of the second part of the gun swing from the first part of the gun suing. The initiation of such release takes place before the perforating gun detonates. When the perforating gun detonates, the second part of the gun string falls to a bottom of the wellbore and the first part of the gun suing is raised to a surface of the wellbore. The detonation of the perforating gun will not shock and break the conveyor.