Borehole measurement of NMR characteristics of earth formation
US5432446A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 29, 1994 |
| Grant date | Jul 11, 1995 |
| Priority date | — |
| Expiry date | Mar 29, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V3/32
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
NMR logging apparatus is provided which produces a strong, static and homogeneous magnetic field B.sub.0 in a Volume of an adjacent formation on one side of the tool to measure nuclear magnetic resonance characteristics thereof at two different depths of investigations. In the preferred embodiment, the tool has an RF antenna mounted on the outside of the metal body of the tool, directing focused oscillating magnetic fields B.sub.1 at said Volume to polarize or tip the magnetic moments of hydrogen nuclei of fluids within rock pores. The same antenna can be used to receive signals of proton precession in the Volume of interest immediately after transmission of the RF polarizing field B.sub.1. One of the NMR readings is employed to compensate for inaccuracies in the other NMR reading to provide an overall improved NMR log.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.