Drilling apparatus

摘要

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.

主权项

1. An apparatus for drilling a wellbore and fracturing the wellbore during the drilling process, comprising:
a lowermost pilot drill bit having a diameter less than a diameter of the wellbore drilled by the apparatus; a reamer coupled with the lowermost pilot drill such that in use the reamer is disposed above the lowermost pilot drill in the wellbore, the reamer having an adjustable drill diameter from a first diameter less than that of the lowermost pilot drill to a second diameter greater than that of the lowermost pilot drill; a body portion coupled with the reamer such that in use the body portion is disposed above the reamer in the wellbore, the 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; and at least one closeable flow channel passing through the body portion and configured to allow fluid to flow up the wellbore through the at least one closeable flow channel when the at least one closeable flow channel is open, wherein the at least one closeable flow channel is configured to close when a force is applied to the body portion to provide for the body portion sealing a top of a pilot hole drilled by the lowermost pilot drill.