Norton Christensen, Inc.

Kelly Knighton

Steven R Radford

J Stanley Davis

An axial bore is defined throughout the hydraulic lift inner barrel. This axial bore is communicated with the interior of the inner tube thereby allowing the interior of the inner tube to be flushed prior to initiation of the coring operation. When the coring operation is begun, flow of drilling fluid to the interior of the inner tube is prevented by allowing a ball dropped within the drill string to seat within a plug through which the communicating axial bore is defined. Once the flow of drilling fluid to the interior of the inner tube is stopped, the coring operation can begin. After the coring operation is completed, a second ball is dropped and allowed to seat within an inner mandrel through which the axial bore of the coring tool is also defined. Once the axial bore of the inner mandrel is closed, drilling fluid is forced into an expansion chamber within a telescopic piston disposed circumferentially outside of the inner mandrel. The piston is connected to the inner tube. Diversion of drilling fluid into the expansion chamber causes the piston to be longitudinally displaced upward with respect to the inner mandrel, and hence with respect to the outer tube of the drill string. The inner tube is thus similarly lifted within the drill string, thereby activating core catchers or any other downhole mechanism coupled directly or indirectly to the inner tube.

Hydraulic inner barrel in a drill string coring tool

A core spring type core catcher and a full closure core catcher are completely concealed from the core within a coring tool. The full closure catcher is reliably actuated to assume a closed configuration without dependence upon gravity or an interference diametrical fit with the core by use of a cam ring which is longitudinally displaced downwardly within the core barrel by a preloaded compression spring. The full closure core catcher is comprised of a plurality of flapper valves circumferentially disposed outside of the inner tube and concealed by the inner tube or a terminal extension of the inner tube. Disposed above the plurality of flapper valves, and also circumferentially disposed outside of and concentric with the inner tube is a cam ring. Similarly circumferentially disposed outside of and concentric with the inner tube is a preloaded coil compression spring bearing against the cam ring. The cam ring in turn is in sliding contact with a rear surface of each one of the plurality of flapper valves. When the inner tube is longitudinally displaced with respect to the flapper valves to uncover the flapper valves, the flapper valves are then rotated inwardly within the inner barrel of the coring tool by virtue of the downward longitudinal drive of the cam ring as powered by the preloaded compression spring.

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West Jordan, UT, United States of America

Kelly Knighton