Ground subsiding wellhead
US4974676A · kind A · utility
5Cited by
7References
19Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Jun 9, 1989 |
| Grant date | Dec 4, 1990 |
| Priority date | — |
| Expiry date | Jun 9, 2009 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B33/0422
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A ground subsidence wellhead has a lower wellhead assembly mounted on the ground for supporting a casing in tension and an upper wellhead assembly threaded to the top of the casing and spaced from the lower wellhead assembly. The lower assembly has a casing head with aconical bowl for receiving a slip. The slip is wedged between the casing head and casing by compression springs acting between the casing head and the slip, and has asymmetrical teeth for engaging the casing to prevent downward, but allow upward, movement of the casing in the slip.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.