| 摘要 |
A wire line core barrel inner tube assembly having a latch body that has a maximum diameter, axial intermediate portion providing a downwardly facing annular shoulder seatable on a drill stem landing ring and a fluid bypass channel extending through the maximum diameter portion and a valving assembly mounted by and cooperating with the latch body for controlling fluid flow through said channel. The valving assembly is operable to a position blocking the bypass channel but permits the inner tube assembly to move down faster than the fluid flow in the drill stem during the time the inner tube assembly moves downwardly in the drill stem. The bypass channel is blocked when the inner tube assembly is seated at the bit end of the drill stem until such time the pressure at the bypass upper port decreases below a preselected value above that at the lower port and thereafer decreased to permit the valving assembly being resiliently moved to open said channel and retain the channel open even though the pressure at the drill stem outer end is increased to that used during the core drilling operation.
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