| 摘要 |
The application is directed to a shoe assembly with a core catcher for retaining a core of an unconsolidated rock or earth formation in a coring barrel. The shoe assembly includes a tube section adapted to fit removably within the core barrel near the coring bit. Two sets of hinged fingers are attached to the inner surface of the tube section on respective circumferential lines which are displaced from each other. The fingers are movable about the hinged ends between an open position in which the fingers do not significantly occlude the passageway, and a closed position in which the fingers do occlude the passageway. The fingers are biased toward the closed position by means of respective springs associated with each finger. When in the closed position, the two sets of fingers together occlude at least 90% of the cross-section of the passageway. The fingers are urged to the open position by the action of a core moving through the coring barrel away from the drilling end. When the motion of the core into the barrel stops and then reverses as the core barrel is withdrawn from the wellbore, the springs exert sufficient force to move the fingers into the core taken from an unconsolidated formation. Continued upward movement of the core barrel drives the fingers through the core material to the closed position. In the closed position, the core catcher holds the core in place in the core barrel during its removal from the drill hole.
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