Methods and apparatus for measuring flow velocity in a wellbore using NMR and applications using same
US6528995B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 10, 2001 |
| Grant date | Mar 4, 2003 |
| Priority date | — |
| Expiry date | Sep 10, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R33/563
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The present invention provides met hods and apparatus for determining flow velocity within a formation utilizing nuclear magnetic resonance (NMR) techniques in which the shape of the resonance region is restricted so that sensitivity to radial flow or vertical flow is obtained (or both when more than one NMR tool is used). Flow velocity using these NMR tools is determined using decay amplitude, frequency displacement or stimulated echoes (where the spins are stored along the magnetic field instead of the transverse plane to exploit echo decays and frequency displacements) based on the application of adiabatic pulses. Based on the described NMR measurement of flow velocity, additional wellbore parameters may be obtained such as a direct measurement of permeability, an assessment of drilling damage to the wellbore, formation pressure, invasion rate of the mud filtrate or the migration of fine mud particles during sampling operations.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.