US4465140A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for the magnetization of well casing
Assignee: Mobil Oil AS
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Filing: 1982-09-28
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Granted: 1984-08-14
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Expires: 2002-09-28
Abstract
Abstract A well casing is magnetized by traversing an internal magnetizer along and within the well casing while periodically reversing the direction of the magnetic field of the magnetizer to create a plurality of magnetic flux leakage points along the well casing.
Inventors
- 👤 Gustave L. Hoehn, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 23:45
CPC Classifications
E; E21; E21B; E21B7/00; E21B7/04; E21B47/00; E21B47/02; E21B47/022; E21B47/0228; G; G01; G01V; G01V3/00; G01V3/08
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
89 words
A method of magnetizing a well casing, comprising the steps of: (a) moving a direct current magnetizing means relative to the well casing to create a magnetic anomaly along said casing, and (b) periodically reversing the direction of the magnetic field of said magnetizing means at each of a plurality of successive spaced points as said magnetizing means moves relative to said casing to create a plurality of spaced and alternating north and south monopoles defining a plurality of spaced magnetic flux leakage points in and along said casing.
Claim 2
Independent Claim
89 words
A method of magnetizing a well casing, comprising the steps of: (a) moving a direct current magnetizing means relative to the well casing to create a magnetic anomaly along said casing, and (b) periodically reversing the direction of the magnetic field of said magnetizing means at each of a plurality of successive spaced points as said magnetizing means moves relative to said casing to create a plurality of spaced and alternating north and south monopoles defining a plurality of spaced magnetic flux leakage points in and along said casing.
Claim 3
Dependent Claim
36 words
The method of claim 1 wherein the distance between said magnetic flux leakage points is such that a desired magnetic field strength is created along said casing at a desired radial distance outward from said casing.
Claim 4
Dependent Claim
33 words
The method of claim 2 wherein said desired magnetic field strength is created at a radial distance outward from said casing at least equal to the distance between said magnetic flux leakage points.
Claim 5
Dependent Claim
25 words
The method of claim 1 wherein said magnetization of the well casing is carried out after the well casing has been set within the wellbore.
Claim 6
Dependent Claim
25 words
The method of claim 1 wherein said magnetization of the well casing is carried out as the well casing is being lowered into the wellbore.
Claim 7
Dependent Claim
22 words
The method of claim 1 wherein the spacing between alternating monopoles in said casing is greater than a radius of said casing.
Claim 8
Dependent Claim
19 words
The method of claim 1 wherein said magnetizing means moves through said well casing to create said magnetic anomaly.
References Cited (Backward Citations)
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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) | 1987-08-14 | 1988-02-13 | 1988-08-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-08-14 | 1992-02-13 | 1992-08-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-08-14 | 1996-02-13 | 1996-08-14 | $7700.00 | Window Closed / Lapsed |