Electromagnetic and magnetostatic shield to perform measurements ahead of the drill bit
US7994790B2 · kind B2 · utility
11Cited by
7References
17Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Mar 10, 2009 |
| Grant date | Aug 9, 2011 |
| Priority date | — |
| Expiry date | Oct 21, 2029 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V3/28
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A transmitter on a bottomhole assembly (BHA) is used for generating a transient electromagnetic signal in an earth formation. A pair of receivers on the BHA receive signals that are indicative of formation resistivity and distances to bed boundaries. A time dependent calibration factor or a time-independent calibration factor may be used to combine the two received signals and estimate the distance to bed boundaries that are unaffected by the drill conductive body. Further improvement can be obtained by using copper shielding.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.