Steerable rotary drill bit assembly with pilot bit

A rotary drill bit assembly suitable for directionally drilling a borehole into an underground formation, the drill bit assembly having a bit body extending along a central longitudinal bit-body axis, and having a bit-body face at its front end, wherein an annular portion of the bit-body face is pro...

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Bibliographic Details
Main Author RUNIA DOUWE JOHANNES,SMITH DAVID GEORGE LIVESEY,WORRALL ROBERT NICHOLAS
Format Patent
LanguageEnglish
Published 07.11.2007
Subjects
EARTH DRILLING
EARTH DRILLING, e.g. DEEP DRILLING
FIXED CONSTRUCTIONS
MINING
OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR ASLURRY OF MINERALS FROM WELLS
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Summary:A rotary drill bit assembly suitable for directionally drilling a borehole into an underground formation, the drill bit assembly having a bit body extending along a central longitudinal bit-body axis, and having a bit-body face at its front end, wherein an annular portion of the bit-body face is provided with one or more chip-making elements; a pilot bit extending along a central longitudinal pilot-bit axis, the pilot bit being partly arranged within the bit body and projecting out of the central portion of the bit-body face, the pilot bit having a pilot-bit face provided with one or more chip-making elements at its front end; a joint means arranged to pivotably connect the pilot bit to the bit body so that the bit-body axis and the pilot-bit axis can form a variable diversion angle; and a steering means arranged to pivot the pilot bit in order to steer the direction of drilling.
Bibliography:Application Number: CN20028014209