Cammed and shrouded core catcher

Abstract

A positively driven full closure core catcher for use with soft or unconsolidated cores is comprised of an inner tube shoe into which a plurality of windows have been cut. In each window is a corresponding one of a plurality of flapper valves. The flapper valves are spring-biased to a withdrawn position outside of the interior of the inner tube shoe. A cam member is in sliding contact with an inclined rear surface of the flapper valve. Longitudinal displacement of the cam member with respect to the inclined surface of the flapper valve causes the cam to ride down the inclined surface of the valve thereby forcing the rotatable flapper valve into the interior of the inner tube shoe and into a fully closed position. The cam member is substantially radially fixed and is selectively disengaged from the inner tube shoe to which it is temporarily coupled by a collet assembly. The collet assembly is coupled to a cylinder on which the cam is fixed. Normally, the collet assembly will keep the cam and cylinder in a fixed longitudinal relationship with respect to the inner tube shoe. However, as the inner barrel is raised the collet latch of the collet assembly contacts a floating outer tube ring which causes the collet latch to bend outwardly and release from the inner tube shoe. The cylinder and cam are then longitudinally fixed within the coring tool and the inner tube and inner tube shoe continue to be longitudinally displaced. This causes the cam to ride down and close the flapper valves.