| 摘要 |
The disclosure provides a method and apparatus for effecting the locking of a well tool in any selected one of a plurality of identical nipples provided in spaced relationship along a well tubing string. Each nipple is provided with an annular recess to receive expandable locking dogs carried by the locking mechanism and an upwardly facing no-go shoulder which is of no lesser diameter than the bore of the tubular string. The locking mechanism is shearably mounted on a running tool and incorporates an expansible C-ring which has a downwardly facing shoulder engagable, when expanded, with the no-go shoulder of the selected locking nipple. The expansible C-ring is held in a retracted position by a collet having spring arms which pass freely downwardly through any or all of the nipples but, when moved upwardly through a selected nipple, engage a surface on the nipple and pull the collet out of its retaining position with respect to the expansible C-ring. The C-ring expands into engagement with the upwardly facing no-go shoulder, thus permitting the application of a downward force to the locking mechanism which effects the shearing of shear pins holding a camming mandrel in an inoperative position with respect to the locking dogs. The camming mandrel is then moved downwardly by the running tool to expand the locking dogs into engagement with the locking recess, following which, the running tool may be removed from the locking mechanism by an upward pull which shears a second shear pin.
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