SAFETY LATCH FOR A DOWNHOLE TOOL

摘要

A lockable overshot assembly for use in a wireline spearhead system for lowering and retrieving inner tube assemblies and other tools and equipment from a downhole location includes a pair of lifting dogs pivotally mounted to an overshot head on the lockable overshot assembly and configured for latching a spearhead. A locking arrangement is mounted into the elongated body and engagable within the lifting dogs, such that in a locked state the lifting dogs are in latched position and in an unlocked state, allows the lifting dogs to move to the release position. The locking arrangement is a pin, which can be moved laterally to be between the latching dogs to prevent them moving to the release position.