Nuclear magnetic resonance logging with azimuthal resolution using gradient coils
US6326784A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 5, 1998 |
| Grant date | Dec 4, 2001 |
| Priority date | — |
| Expiry date | Nov 5, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R33/385
- 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. At least one gradient coil is positioned circumferentially around the tool. A magnetic field is produced by the coil in a region of the formation facing the coil. The magnetic field is substantially parallel to the static magnetic field produced by a pair of permanent magnets which form a part of the tool. The additional field causes an additional phase shift for spins located in the region so that the spins subjected to the additional field do not form a spin-echo.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.