Importance

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Abstract

A mechanism for catching and holding a core within an inner tube in a drill string includes a slidable core catcher and a full closure core catcher. The slidable core catcher is disposed within the inner tube and is coupled to an inner tube ring concentrically mounted on the outside of the inner tube. The inner tube ring and the slidable core catcher are connected to each other by means of a shear pin slidable within a slot defined in the inner tube. An outer tube ring is connected to the outer tube concentrically disposed about the inner tube. When the outer tube ring contacts the inner tube ring as the inner tube is lifted, the inner tube ring is moved downwardly with respect to the inner tube, thereby pulling the core catcher with it. As the core catcher moves downwardly it is compressed by an inside conical surface provided near the end of the inner tube. This serves to effectuate operation of the slideable core catcher. As the slidable core catcher is moved downwardly its upper edge will clear the lower surfaces of a spring loaded full closure catcher which is formed in the shape of a cusped flapper valve. Thus, when the slidable core catcher has been longitudinally displaced with respect to the inner tube by a predetermined distance the full closure catcher will, in the case of an unconsolidated core, close completely and thereby retain the unconsolidated core within the inner tube.

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First Claim