Controlling backflow pressure during retrieval of bottom hole assembly
US7779920B2 · kind B2 · utility
1Cited by
3References
20Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | May 22, 2008 |
| Grant date | Aug 24, 2010 |
| Priority date | — |
| Expiry date | Aug 7, 2028 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B23/14
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A bottom hole assembly in a casing-while-drilling operation is retrieved by displacing the fluid in the casing string with a less dense fluid than the fluid in the annulus. The bottom hole assembly moves upward in the casing string in response to an upward force due to the different densities of fluid in the casing string and in the annulus. Displaced fluid flows out of the casing string and through a restrictive orifice of a choke. The flow area of the orifice is varied as the bottom hole assembly moves upward to control the rate at which the bottom hole assembly moves upward.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.