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US4987368A
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Nuclear magnetism logging tool using high-temperature superconducting squid detectors
Assignee: Shell USA Inc
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Filing: 1989-08-31
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Granted: 1991-01-22
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Expires: 2009-08-31
Abstract
Abstract A logging device is disclosed for measuring the nuclear magnetism response of earth formations. The device employs a detector that is capable of detecting sinusoidal and slowly varying changes in magnetic field caused by precession of mobile nuclei about the earth's magnetic field. Such a detector may be one or more laser-pumped helium magnetometers, or one or more high-temperature Superconducting Quantum Interference Devices (SQUID). The invention uses a micro-miniature Joule-Thomson refrigerator to maintain the high-temperature SQUIDs below their superconducting transition point. The SQUIDs are flux coupled in an axial gradiometer configuration to reduce motion-induced magnetic noise.
Inventors
- 👤 Harold J. Vinegar
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 10:02
CPC Classifications
G; G01; G01V; G01V3/00; G01V3/18; G01V3/32
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
76 words
A nuclear magnetism logging tool, comprising: means for providing a magnetic field that is capable of being energized or de-energized in response to preselected control signals, detector means for essentially simultaneously detecting both sinusoidal and slowly varying near D.C. changes in magnetic field when said means for providing a magnetic field is de-energized and outputting signals indicative thereof, and and electronics package for generating said preselected control signals and for receiving signals from said detector means.
Claim 2
Dependent Claim
76 words
A nuclear magnetism logging tool, comprising: means for providing a magnetic field that is capable of being energized or de-energized in response to preselected control signals, detector means for essentially simultaneously detecting both sinusoidal and slowly varying near D.C. changes in magnetic field when said means for providing a magnetic field is de-energized and outputting signals indicative thereof, and and electronics package for generating said preselected control signals and for receiving signals from said detector means.
Claim 3
Dependent Claim
19 words
A nuclear magnetism logging tool as described in claim 1, wherein said detector means is a laser-pumped helium magnetometer.
Claim 4
Dependent Claim
21 words
A nuclear magnetism logging tool as described in claim 1, wherein said detector means is a superconducting quantum interference device (SQUID).
Claim 5
Dependent Claim
34 words
A nuclear magnetism logging tool as described in claim 3, further comprising means for cooling said SQUID detector means for maintaining it at a temperature below the superconducting transition temperature of its superconducting material.
Claim 6
Dependent Claim
22 words
A nuclear magnetism logging tool as described in claim 1, wherein said means for providing a magnetic field is a solenoidal coil.
Claim 7
Dependent Claim
18 words
A nuclear magnetism logging tool as described in claim 3, wherein said SQUID employs a high-temperature superconducting material.
Claim 8
Dependent Claim
20 words
A nuclear magnetism logging tool as described in claim 4, wherein said means for cooling employs a Joule-Thomson refrigeration cycle.
Claim 9
Dependent Claim
20 words
A nuclear magnetism logging tool as described in claim 6, wherein said high-temperature superconducting material is substantially an oxygen-deficient perovskite.
Claim 10
Dependent Claim
24 words
A nuclear magnetism logging tool as described in claim 8, wherein said high-temperature superconducting material is substantially YBa 2 Cu 3 O 7 .
Claim 11
Dependent Claim
55 words
A nuclear magnetism logging tool as described in claim 3 further comprising: a pair of superconducting axial gradiometer detector coils flux coupled to said SQUID, and wherein one of said coils is disposed within the means for providing a magnetic field and the other coil is disposed outside the means for providing a magnetic field.
Claim 12
Dependent Claim
19 words
A nuclear magnetism logging tool as described in claim 10, further comprising a superconducting shield disposed around said SQUID.
Claim 13
Dependent Claim
27 words
A nuclear magnetism logging tool as described in claim 4, wherein said SQUID and means for cooling are mounted adjacent each other on a thermally conductive substrate.
Claim 14
Dependent Claim
17 words
A nuclear magnetism logging tool as described in claim 12, wherein said substrate is SrTiO 3 .
Claim 15
Dependent Claim
15 words
A nuclear magnetism logging tool as described in claim 12, wherein said substrate is MgO.
Claim 16
Independent Claim
44 words
A method for nuclear magnetism logging, comprising: generating a magnetic field in a borehole, removing said magnetic field, and then essentially simultaneously detecting both the sinusoidal and slowly varying near D.C. magnetic fields resulting from precession of mobile nuclei about the earth's magnetic field.
Claim 17
Independent Claim
44 words
A method for nuclear magnetism logging, comprising: generating a magnetic field in a borehole, removing said magnetic field, and then essentially simultaneously detecting both the sinusoidal and slowly varying near D.C. magnetic fields resulting from precession of mobile nuclei about the earth's magnetic field.
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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) | 1994-01-21 | 1994-07-23 | 1995-01-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-01-21 | 1998-07-23 | 1999-01-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-01-21 | 2002-07-23 | 2003-01-22 | $7700.00 | Window Closed / Lapsed |