US5376884A
Expired / Lapsed
US
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Nuclear magnetic resonance measuring apparatus
Assignee: Schlumberger Technology Corp
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Filing: 1993-04-01
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Granted: 1994-12-27
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Expires: 2013-04-01
Abstract
Abstract The disclosure invention is directed to a nuclear magnetic resonance measurement apparatus that can be utilized in a logging device which operates generally centrally in a borehole, and has a generally circumferential region of investigation, but which permits usage of relatively powerful permanent magnets, such as rare-earth magnets, that are not permeable to the RF magnetic field. This is achieved by employing side-by-side spaced apart elongated magnets, and an RF current loop in the region between the magnets. In a disclosed embodiment, the magnets are each in the shape of a segment of a cylinder, and the respective axes of elongation of the magnets are parallel. The magnets have respective casings with electrically conductive surfaces, and the RF current loop includes at least a portion of the conductive surfaces of the magnet casings.
Inventors
- 👤 Abdurrahman Sezginer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-10 01:49
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/28; G01R33/38; G01R33/3808; G01R33/32; G01R33/34; G01V; G01V3/00; G01V3/18; G01V3/32
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
107 words
Apparatus for measuring a nuclear magnetic resonance property of formations surrounding an earth borehole, comprising: a generally cylindrical housing moveable through the borehole; a plurality of spaced apart elongated magnet assemblies disposed in said housing in side-by-side spaced-apart arrangement; each of said magnet assemblies comprising a rare-earth permanent magnet body within an electrically conductive magnet casing; an RF current loop disposed in said housing in the region between said assemblies, the RF current loop including at least a portion of each of the magnet casings; means for coupling RF energy to said RF current loop; and means for detecting RF signals induced in said RF current loop.
Claim 2
Dependent Claim
107 words
Apparatus for measuring a nuclear magnetic resonance property of formations surrounding an earth borehole, comprising: a generally cylindrical housing moveable through the borehole; a plurality of spaced apart elongated magnet assemblies disposed in said housing in side-by-side spaced-apart arrangement; each of said magnet assemblies comprising a rare-earth permanent magnet body within an electrically conductive magnet casing; an RF current loop disposed in said housing in the region between said assemblies, the RF current loop including at least a portion of each of the magnet casings; means for coupling RF energy to said RF current loop; and means for detecting RF signals induced in said RF current loop.
Claim 3
Dependent Claim
20 words
Apparatus as described as defined by claim 1, wherein the respective axes of elongation of said magnet assemblies are parallel.
Claim 4
Dependent Claim
21 words
Apparatus as defined by claim 2, wherein said magnet assemblies are each in the shape of a segment of a cylinder.
Claim 5
Dependent Claim
20 words
Apparatus as defined by claim 1, wherein said RF current loop further includes a conductor coupled between respective magnet casings.
Claim 6
Dependent Claim
22 words
Apparatus as defined by claim 4, wherein said RF current loop further includes at least one capacitor coupled between the magnet casing.
Claim 7
Dependent Claim
21 words
Apparatus as defined by claim 1, wherein said magnet assemblies extend longitudinally beyond both longitudinal extremes of said RF current loop.
Claim 8
Dependent Claim
26 words
Apparatus as defined by claim 1, wherein each of said magnet casings comprises a metal inner layer, an insulating interlayer, and an outer metal foil layer.
Claim 9
Dependent Claim
44 words
Apparatus as defined by claim 1, wherein said magnet bodies are magnetized in a direction perpendicular to their longitudinal direction, and said RF loop is oriented to produce magnetic field lines that are orthogonal to static magnetic field lines produced by said magnet bodies.
Claim 10
Dependent Claim
20 words
Apparatus as defined by claim 2, wherein said RF current loop further includes a conductor coupled between respective magnet casings.
Claim 11
Dependent Claim
22 words
Apparatus as defined by claim 9, wherein said RF current loop further includes at least one capacitor coupled between the magnet casing.
Claim 12
Dependent Claim
97 words
Apparatus for measuring a nuclear magnetic resonance property of formations surrounding an earth borehole, comprising: a logging device moveable through the borehole; first and second elongated permanent magnets disposed in said logging device in side-by-side spaced-apart arrangement, said magnets have respective casings with electrically conductive surfaces thereon; an RF current loop disposed in the region between said magnets, said RF current loop including at least a portion of the conductive surfaces of said magnet casings; means for coupling RF energy to said RF current loop; and means for detecting RF signals induced in said RF current loop.
Claim 13
Dependent Claim
97 words
Apparatus for measuring a nuclear magnetic resonance property of formations surrounding an earth borehole, comprising: a logging device moveable through the borehole; first and second elongated permanent magnets disposed in said logging device in side-by-side spaced-apart arrangement, said magnets have respective casings with electrically conductive surfaces thereon; an RF current loop disposed in the region between said magnets, said RF current loop including at least a portion of the conductive surfaces of said magnet casings; means for coupling RF energy to said RF current loop; and means for detecting RF signals induced in said RF current loop.
Claim 14
Dependent Claim
17 words
Apparatus as defined by claim 11, wherein the respective axes of elongation of said magnets are parallel.
Claim 15
Dependent Claim
20 words
Apparatus as defined by claim 12, wherein said magnets are each in the shape of a segment of a cylinder.
Claim 16
Dependent Claim
21 words
Apparatus as defined by claim 11, wherein said permanent magnets extend longitudinally beyond both longitudinal extremes of said RF current loop.
Claim 17
Dependent Claim
13 words
Apparatus as defined by claim 11, wherein said permanent magnets are rare-earth magnets.
Claim 18
Dependent Claim
44 words
Apparatus as defined by claim 11, wherein said permanent magnets are magnetized in a direction perpendicular to their longitudinal direction, and said RF loop is oriented to produce magnetic field lines that are orthogonal to static magnetic field lines produced by said permanent magnets.
Claim 19
Dependent Claim
31 words
Apparatus as defined by claim 11 wherein said magnets are magnetized in a direction perpendicular to their longitudinal direction and perpendicular to the radial direction of the gap between the magnets.
Claim 20
Dependent Claim
14 words
Apparatus as defined by claim 11 wherein said electrically conductive surfaces comprise copper sheets.
Claim 21
Dependent Claim
21 words
Apparatus as defined by claim 11 wherein said permanent magnets extend longitudinally beyond both longitudinal extremes of said RF current loop.
Claim 22
Dependent Claim
24 words
Apparatus as defined by claim 11, wherein said RF current loop further includes a conductor coupled between conductive surfaces of respective magnet casing surfaces.
Claim 23
Dependent Claim
26 words
Apparatus as defined by claim 20, wherein said RF current loop further includes at least one capacitor coupled between conductive surfaces of respective magnet casing surfaces.
Claim 24
Dependent Claim
91 words
Apparatus for measuring a nuclear magnetic resonance property of formations surrounding an earth borehole, comprising: a logging device moveable through the borehole; first and second elongated permanent magnets having parallel axes of elongation and being disposed in said logging device in side-by-side spaced-apart arrangement, each of said magnets being in the shape of a segment of a cylinder; an RF current loop disposed in the region between said magnets; means for coupling RF energy to said RF current loop; and means for detecting RF signals induced in said RF current loop.
Claim 25
Dependent Claim
91 words
Apparatus for measuring a nuclear magnetic resonance property of formations surrounding an earth borehole, comprising: a logging device moveable through the borehole; first and second elongated permanent magnets having parallel axes of elongation and being disposed in said logging device in side-by-side spaced-apart arrangement, each of said magnets being in the shape of a segment of a cylinder; an RF current loop disposed in the region between said magnets; means for coupling RF energy to said RF current loop; and means for detecting RF signals induced in said RF current loop.
Claim 26
Dependent Claim
50 words
Apparatus as described by claim 22, wherein said magnets have respective casings with electrically conductive surfaces thereon, and wherein said RF current loop includes at least a portion of the conductive surfaces of said magnet casings, and further includes a conductor coupled between conductive surfaces of respective magnet casing surfaces.
Claim 27
Dependent Claim
26 words
Apparatus as defined by claim 23, wherein said RF current loop further includes at least one capacitor coupled between conductive surfaces of respective magnet casing surfaces.
Claim 28
Dependent Claim
21 words
Apparatus as defined by claim 23, wherein said permanent magnets extend longitudinally beyond both longitudinal extremes of said RF current loop.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-12-26 | 1998-06-27 | 1998-12-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-12-26 | 2002-06-27 | 2002-12-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-12-26 | 2006-06-27 | 2006-12-27 | $7700.00 | Window Closed / Lapsed |