Apparatus and method for snubbing tubing-conveyed perforating guns in and out of a well bore

摘要

Appts. for use in connecting sections of a perforating gun string, comprises (a) an upper mandrel for connecting to an upper section of the gun string; (b) a lower mandrel engaged with the upper mandrel by a left-hand threaded connection, for connecting to a lower section of the gun string; and (c) means for initially preventing disengagement of the upper mandrel from the lower mandrel by right-hand rotation and for allowing disengagement upon application of a predetermined torque on the upper mandrel; in which (d) the means for initially preventing disengagement is a ratchet connected to the upper mandrel and allowing left-hand rotation of the mandrel and ratchet w.r.t. the lower mandrel and further for preventing right-hand rotation of the ratchet w.r.t. the lower mandrel. Also claimed are (i) an appts. for connecting a pair of perforating guns; (ii) a method of snubbing perforating guns into a well under pressure; and (iii) a method of retrieving perforating guns from a well under pressure.