Schlumberger Technology Corporation

Thomas M Sayers

Klaus B Huber

A Glen Edwards

Edward G Smith, Jr

A firing head adapted to connected between a coiled tubing and a perforating gun, is sized and shaped to enable it to move freely within a tubing string in the wellbore, may be actuated by fluid pressure within the coiled tubing, and includes a circulation and recirculation feature wherein wellbore fluid may be circulated through the firing head between the coiled tubing and an annulus around the tubing string, the circulation taking place either before or after detonation of the perforating gun. Three firing heads are discussed. One such firing head is a Circulation Direction Firing (CDF) Head. The CDF firing head circulates fluid from the wellbore to the coiled tubing and depresses a piston. Then, fluid pressure from the coiled tubing lifts the piston uncovering locking balls and propelling a firing pin to a booster of a detonating cord detonating the CDF firing head. Fluid circulation from the coiled tubing to the wellbore annulus begins after the CDF firing head detonates. Another such firing head is a Circulation Ball Firing (CBF) Head. The CBF firing head circulates fluid from the wellbore to the coiled tubing, receives a ball, and uses fluid pressure in the coiled tubing to lift a piston, uncover the locking balls and detonate the CBF firing head. Another such firing head is a Ball Actuated Circulation Firing (BCF) Head. The BCF firing head circulates fluid from the wellbore to the coiled tubing, receives a ball from the wellbore surface, and uses fluid pressure in the coiled tubing to push a piston downwardly which uncovers the locking balls and detonates the BCF firing head. Recirculation is permitted after the firing head detonates.

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Houston, TX, United States of America

Thomas M Sayers