Drilling with casing and retrievable drill bit
US5271472A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 14, 1992 |
| Grant date | Dec 21, 1993 |
| Priority date | — |
| Expiry date | Oct 14, 2012 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B10/322
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
Wellbores are formed in the earth with elongated, tubular drillstems which include retrievable bit assemblies. The retrievable bit assembly includes a body having locking dogs engageable with cooperating recesses formed in a sub at the bottom of the drillstem. The bit assembly includes radially extendable and retractable arms with cutters thereon for forming the wellbore to a diameter greater than the drillstem, but whereby the arms may be retracted to withdraw the bit assembly through the drillstem with wireline retrieval apparatus or the like. The wellbore may be drilled with a tubular drillstem comprising wellbore casing with a bit connected to the lower end of the drillstem and retrievable through the drillstem by the wireline retrieval apparatus whereby the casing may be left in the wellbore upon completion of drilling operations.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.