Temperature compensated magnetic field apparatus for NMR measurements
US6577125B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 18, 2000 |
| Grant date | Jun 10, 2003 |
| Priority date | — |
| Expiry date | Dec 18, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V3/32
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An apparatus is disclosed for generating a magnetic field of high field strength, spatial uniformity and minimal drift of magnetic field intensity over a temperature range of about 0° C. to 175° C. This apparatus may be used in a standard modular logging tool for direct downhole NMR measurements of various parameters of fluid samples of geologic formations near the walls of a borehole. In one embodiment, the apparatus is composed of two tubular permanent magnets made of different magnetic materials with different magnetic temperature coefficients to provide temperature compensation. The apparatus preferably also utilizes a pressure barrel that surrounds the magnets and provides a return path for magnetic flux lines, thereby increasing flux density within the measurement volume.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.