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Title:
DRILLING RIG
Document Type and Number:
WIPO Patent Application WO1997021902
Kind Code:
A3
Abstract:
An improved drilling rig having a drillhead assembly positioned onto a mast for vertical movement therewith. The drillhead assembly is hung by cables threaded from a hoist assembly positioned at the top end of the mast. One or more cable return assemblies are positioned at the bottom end of the mast. The cables are counter-wound on the hoist assembly such that the cables roll off of the hoist assembly in the direction towards the drillhead assembly at the same rate the cables are pulled onto the hoist assembly from the direction towards the cable return assemblies. The drillhead assembly has a drive motor assembly rotatably mounted within a frame. A break-out tool assembly is mounted at the lower end of the mast. The break-out tool assembly has means for grasping rotating a length of string so as to separate the lengths of string.

Inventors:
CANEER CLIFFORD JR
DYCUS WILLIAM V
Application Number:
PCT/US1996/019484
Publication Date:
August 07, 1997
Filing Date:
December 09, 1996
Export Citation:
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Assignee:
BOART LONGYEAR COMPANY (US)
International Classes:
E21B19/084; E21B19/15; E21B19/16; E21B19/20; (IPC1-7): E21B19/16; E21B19/08; E21B19/20
Foreign References:
EP0009639A21980-04-16
US3780883A1973-12-25
US3682259A1972-08-08
DE8528104U11985-12-19
DE2812096A11979-04-12
US3717205A1973-02-20
US4150727A1979-04-24
US5004055A1991-04-02
US4890681A1990-01-02
US4024925A1977-05-24
US4434860A1984-03-06
Other References:
MCGHEE: "Two-man crew operates hydraulic rig", THE OIL AND GAS JOURNAL, vol. 56, no. 38, 22 September 1958 (1958-09-22), TULSA, OKLA, USA, pages 92 - 98, XP002028732
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