Positive indication shear ring

Abstract

A positive position indicating tool includes a snap ring mounted on a mandrel. The snap ring is blocked on the mandrel by a shear sleeve and provides a positive stop to upward retraction of a work string. The snap ring is shearably released when it is desired to retract and/or retrieve the work string. The snap ring is supported on the mandrel by a shear sleeve which is locked onto the mandrel by shear pins. An annular recess is formed in the sidewall of the mandrel between the shear pins and the snap ring. As the tension loading on the work string increases above the combined shear strength of the shear pins, the shear sleeve and positive indication snap ring are displaced downwardly along the mandrel, and the snap ring moves into the annular recess and contracts radially out of obstructing engagement. The snap ring incorporates alternating slots which permit it to expand and recover without permanent deformation. The slots are angularly displaced from a large angle at the back of the ring to progressively smaller displacement angles toward the open end portions of the ring. The slots are more widely separated and are shallower in the high stress regions of the snap ring, and are more closely located and are deeper in the low stress regions of the ring.