Drilling apparatus
AssigneeSchlumberger Technology Corporation
InventorsBenjamin Peter Jeffryes, Ashley Bernard Johnson
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Abstract
An apparatus for drilling a wellbore (10) is disclosed, the apparatus comprising a lowermost pilot drill bit (16) having a diameter less than that of the diameter of wellbore (12) drilled by the apparatus, above which is a reamer, having an adjustable drill diameter from a first diameter less than that of the pilot drill to a second diameter greater than that of the pilot drill, above which is a body portion (24) having a lower diameter less than that of the pilot drill and an upper diameter greater than that of the pilot' drill but less than the second diameter of the reamer.
Claims20
An apparatus for drilling a wellbore comprising a lowermost pilot drill bit having a diameter less than that of the diameter of wellbore drilled by the apparatus, above which is a reamer, having an adjustable drill diameter from a first diameter less than that of the pilot drill to a second diameter greater than that of the pilot drill, above which is a body portion having a lower diameter less than that of the pilot drill and an upper diameter greater than that of the pilot drill but less than the second diameter of the reamer.
Dependencies are inferred from the claim text.