Dropping the gun string immediately after firing offers several benefits over using slickline shifting tools or pressure-activated release tools. Advantages include preventing the gun string from becoming stuck in weak sands during perforating, enabling efficient post-perforation cleanup in permanent completions, and eliminating the challenges of dropping guns in highly deviated wells. After detonation, the pressure from the gun causes the shifting sleeve to move and make contact with the retainer ring. The brass retainer screws shear, allowing the shifting sleeve and retainer ring to move upward, freeing the finger release sub and enabling the mandrel to move freely as well. The atmospheric pressure chamber between the mandrel and shifting sleeve pulls the mandrel into the sleeve, effectively pushing the gun out of the release sub. This dual action requires minimal gun weight to release the assembly successfully. Once released, the gun string and firing head drop, exposing the wireline entry guide. Tubing and rathole pressures must be equalized to prevent the gun string from becoming hydraulically locked in the release sub. The dropped gun string and firing head assembly feature a slick fishing profile, allowing for easy retrieval at a later time.
