A bi-centre bit for drilling out through a casing shoe
Kind Code:
B1
Abstract of EP1270868
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.
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.
Inventors:
Watson, Graham R. (GB)
Hart, Steven James (GB)
Hart, Steven James (GB)
Application Number:
EP20020014475
Publication Date:
09/14/2005
Filing Date:
10/26/2000
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Export Citation:
Assignee:
CAMCO INT UK LTD (GB)
International Classes:
E21B10/26; E21B10/26; E21B17/00; E21B17/10; (IPC1-7): E21B10/26; E21B7/06; E21B10/42
European Classes:
E21B17/10Z; E21B10/26