Method and apparatus for drilling in permafrost and the like
An auger-type drill is described which is complemented by a pilot percussion apparatus that is substantially smaller in diameter than the auger. This apparatus is particularly suited for drilling in regions having permafrost. The relatively large auger has at least one helical flight which is welded to a long central tube. The upper end of the auger has a shape such that torque may be readily applied for rotation of the auger. Interiorly of the upper end of the tube is a means for mounting a downhole percussion hammer such that the percussion hammer may be suspended for operation within the tube. Preferably, a substantially solid drill bit having a generally frustoconical (pointed) shape is used in conjunction with the percussion hammer. More compressed air is admitted to the bottom of the hole than would normally be admissible by relying on air supplied to the percussion hammer alone. The helical flight adjacent the periphery of the tube may be replaced by arc-shaped segments that are axially spaced and off-set with respect to each other along the tube. Cuttings which are blown part of the way out of a hole being drilled will tend to accumulate on top of these segments. Lifting the apparatus out of the hole will remove the captured cuttings. (9 claims)
- Assignee:
- EDB-83-051252
- Patent Number(s):
- US 4061197
- OSTI ID:
- 6460788
- Country of Publication:
- United States
- Language:
- English
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