Enlarged borehole drilling method and apparatus
US4354559A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 30, 1980 |
| Grant date | Oct 19, 1982 |
| Priority date | — |
| Expiry date | Jul 30, 2000 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B21/16
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A method and apparatus are disclosed for drilling a bore hole using a dual concentric drill pipe. Air is supplied through the outer pipe to the bit to cool the bit and jet cuttings upwardly in the bore hole to a suction inlet leading from the bore hole to the inner pipe. A negative pressure is applied to the inner pipe to bail the cuttings up the inner pipe. Makeup air flows down the annulus in the bore hole to the suction inlet and prevents upward movement of dust in the bore hole. A bore hole enlarging bit is disclosed and has expansible cutters which are expanded by hydraulic fluid pressure. In one form, the expansible cutters can also be retracted by hydraulic fluid pressure. The enlarging bit is employed to enlarge a pilot bore hole from a selected beginning location to the bottom of the pilot bore hole to form a blast chamber.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.