Nuclear magnetic resonance logging with azimuthal resolution
US6255817A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 9, 1998 |
| Grant date | Jul 3, 2001 |
| Priority date | — |
| Expiry date | Jun 9, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R33/5612
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The present invention relates generally to an apparatus and method for obtaining an azimuthally resolved nuclear magnetic resonance measurement of an earth formation traversed by a borehole. The measurement can be made while drilling or using a wireline tool. A receiving rf antenna having a non-axisymmetric response pattern is used to obtain the azimuthally resolved nuclear magnetic resonance measurement. The antenna employs axial currents which excite an azimuthally oriented rf magnetic field. For this situation, the static magnetic field is either radial or axial in its orientation. The antenna generates a relatively long, in axial extent, region of generally uniform static field magnitude and polarization in the formation. The present invention facilitates low profile antenna configurations that can permit dispensing with the reduction of the inner diameter of the drill collar at the rf antenna location.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.