Enlarged bore hole drilling method
US4219087A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 18, 1979 |
| Grant date | Aug 26, 1980 |
| Priority date | — |
| Expiry date | Jan 18, 1999 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B21/16
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
The method is disclosed for drilling a pilot hole and subsequently enlarging the pilot hole in earth formation. A dual concentric pipe string is used for circulating air downwardly through the outer pipe, through a pilot bit and upwardly through the bore hole outside the pipe string to bail cuttings, during drilling of the pilot hole. The air pressure expands the cutters of an expansible bit while a milited portion of the air supplied cools the cutters. After the cutters are fully expanded, additional air is utilized to clean and cool the cutters. Air is returned through the inner pipe of the dual concentric pipe string. A venturi device is utilized to induce return flow through the inner pipe during enlargement of the hole and to vacuum residue when enlargement is completed. The dual concentric pipe string is made up of lengths of pipe providing threaded, sealed joints.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.