Mechanical latching device operated by dead weight and tension

Abstract

A mechanical latching device for repeatable latching and unlatching of downhole well tools is adapted for use in a mandrel interconnected with a tubing string of a well, the mandrel forming a downwardly directed internal shoulder. The latch mechanism incorporates a fishing neck adapted for interconnection with the downhole tool. The fishing neck is disposed in upstanding generally centralized relation within the mandrel. A collet member which may be a component part of a well service tool or which may be a component part of the latch mechanism defines pulling shoulders at the free extremity of collet fingers defined thereby. A latch retainer is disposed in movable relation about the fishing neck and is movable between latched and unlatched positions relative to the fishing neck. In the latched position the latch retainer provides external support for the collet fingers to maintain the collet fingers in latching interengagement with a pulling flank. The pulling flank may be defined either by an enlargement of the fishing neck or by an enlargement formed at the lower end of a latch actuator interconnected with the well service tool. The latch apparatus becomes latched responsive to the dead weight of the well service tool and becomes unlatched by tension applied through the well service tool.