Well casing flotation device and method
US5181571A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 10, 1992 |
| Grant date | Jan 26, 1993 |
| Priority date | — |
| Expiry date | Feb 10, 2012 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B31/035
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A ported float shoe (5) and a landing collar (16) are attached at a first end of a portion of a casing string (4) and a sliding air trapping insert (20) is attached at the other end. The air trapping insert (20) includes a fluid flow passageway (24) blocked by a plug (22) attached by shear pins to the insert (20) or the air trapping insert is an inflatable insert (55) having a conduit (60) providing a fluid passageway to the first end. The air trapping insert and float shoe form an air cavity (12a or 12b) within the string portion (4). The air cavity provides buoyant forces during running, cementing or other casing operations within a borehole (2), reducing running drag and the related chance of a differentially stuck casing (4). It also allows reciprocation and rotation during cementing and avoids separate removal steps.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.