A bi-centre bit for drilling out through a casing shoe

The present invention is a bi-center drill bit designed to drill out the cement and other material in the casing and then proceed to drill out the full gauge drilling diameter borehole with a diameter greater than the inside of the casing. The bi-center drill bit is configured with non-drilling bear...

Ausführliche Beschreibung

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Bibliographische Detailangaben
Hauptverfasser:	WATSON, GRAHAM R, HART, STEVEN JAMES
Format:	Patent
Sprache:	eng ; fre ; ger
Schlagworte:	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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Beschreibung
Zusammenfassung:	The present invention is a bi-center drill bit designed to drill out the cement and other material in the casing and then proceed to drill out the full gauge drilling diameter borehole with a diameter greater than the inside of the casing. The bi-center drill bit is configured with non-drilling bearing elements (68,168) that contact with the casing when the bit is drilling the cement without allowing the gauge cutting elements (24,124) of the bi-center drill bit to contact the casing. The bi-center drill bit also has a cutting element configuration which prevents reverse scraping of the cutting elements when drilling both the cement and the formation.