US4792756A
Expired / Lapsed
US
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Method and apparatus for measuring axially extending defects in ferromagnetic elements
Assignee: Varco LP
•
Filing: 1987-05-04
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Granted: 1988-12-20
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Expires: 2007-05-04
Abstract
Abstract A method and apparatus for determining the extent of axially extending defects in ferromagnetic elements, such as tubing comprising a continuous string for use in an oil or gas well is disclosed. The tubing trip tool detects axial defects, such as sucker rod wear during removal of the tubing from the well. A saturating magnetic field and a fluctuating magnetic field are applied to the tubing and the magnitude of the induced fields and the changes are measured to quantify defects in the tubing.
Inventors
- 👤 Clive C. Lam
- 👤 Marvin Milewits
- 👤 James E. Bradfield
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 12:09
CPC Classifications
E; E21; E21B; E21B17/00; E21B17/006; E21B47/00; E21B47/006; E21B47/09; E21B47/092; G; G01; G01N; G01N27/00; G01N27/72; G01N27/82; G01N27/90; G01N27/904
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
203 words
Apparatus for determining the extent of axially-extending defects in an element during axial movement of the element, comprising: means transversely spaced from the element for applying a first magnetizing field along a portion of the axially moving element; a first fixed electrical conductor means traversely spaced from the axially moving element and having a first sinusoidally-shaped conductor cross-sectional distribution around the element for applying a fluctuating magnetic field to the portion of the axially moving element in addition to the first magnetizing field; a second fixed electrical conductor means having a second sinusoidally-shaped conductor cross-sectional distribution around the element of a different phase from the first sinusoidally-shaped conductor distribution for cooperating with the first conductor means for applying the fluctuating magnetic field of a substantially constant magnitude; means traversely spaced from the axially moving element for detecting the driven field induced in the portion of the axially moving element by the fluctuating magnetic field; means for comparing a phase angle of the fluctuating magnetic field to a phase angle of the driven field; and means for correlating the difference between the phase angles of the fluctuating magnetic field and the driven field to determine the extent of defects in the axially moving element.
Claim 2
Dependent Claim
203 words
Apparatus for determining the extent of axially-extending defects in an element during axial movement of the element, comprising: means transversely spaced from the element for applying a first magnetizing field along a portion of the axially moving element; a first fixed electrical conductor means traversely spaced from the axially moving element and having a first sinusoidally-shaped conductor cross-sectional distribution around the element for applying a fluctuating magnetic field to the portion of the axially moving element in addition to the first magnetizing field; a second fixed electrical conductor means having a second sinusoidally-shaped conductor cross-sectional distribution around the element of a different phase from the first sinusoidally-shaped conductor distribution for cooperating with the first conductor means for applying the fluctuating magnetic field of a substantially constant magnitude; means traversely spaced from the axially moving element for detecting the driven field induced in the portion of the axially moving element by the fluctuating magnetic field; means for comparing a phase angle of the fluctuating magnetic field to a phase angle of the driven field; and means for correlating the difference between the phase angles of the fluctuating magnetic field and the driven field to determine the extent of defects in the axially moving element.
Claim 3
Dependent Claim
34 words
The apparatus as defined in claim 1, wherein the means for applying a first magnetizing field comprises: a saturating DC drive coil for applying a saturated magnetic field to the portion of the element.
Claim 4
Dependent Claim
47 words
The apparatus as defined in claim 1, wherein the means for detecting the driven field comprises: first and second detector coils each encircling the axially moving element and having axially extending segments located at a plurality of spaced-apart locations around the periphery of the axially moving element.
Claim 5
Dependent Claim
39 words
The apparatus as defined in claim 3, wherein each of the detector coils has a sinusoidally-shaped conductor cross-sectional distribution, and the first coil has a sine conductor cross-sectional distribution and the second coil has a cosine conductor cross-sectional distribution.
Claim 6
Dependent Claim
35 words
The apparatus as defined in claim 2, further comprising: means for detecting magnetic flux generated by the saturated magnetic field in the axially moving element to determine wall thickness variations along the axially moving element.
Claim 7
Dependent Claim
31 words
The apparatus as defined in claim 2, further comprising: means for detecting flux leakage in the saturated magnetic field to measure the depth of local defects in the axially moving element.
Claim 8
Dependent Claim
31 words
The apparatus as defined in claim 1, wherein the distribution of the first conductor around the tubing is offset approximately 90° from the distribution of the second conductor around the tubing.
Claim 9
Dependent Claim
193 words
A tool for determining the extent of defects in ferromagnetic tubing sections, comprising a continuous tubing string used in a subterranean well bore, at the wellhead as the tubing string travels into or out of the well bore, comprising: a fixed electrical conductor means traversely spaced from the tubing string and having a sinusoidally-shaped conductor cross-sectional distribution around the tubing string for applying a fluctuating magnetic field to a portion of the tubing string; detection means traversely spaced from the tubing string for detecting the driven field induced in the tubing string by the fluctuating magnetic field, the detection means including first and second coils each encircling the tubing string and having a sinusoidally-shaped conductor cross-sectional distribution and axially extending segments located at a plurality of spaced-apart locations around the periphery of the tubing string, the first coil having a sine conductor cross-sectional distribution and the second coil having a cosine conductor cross-sectional distribution; means for comparing a phase angle of the driven field; and means for correlating the difference between the phase angles of the fluctuating magnetic field and the driven field to determine the extent of defects in the tubing string.
Claim 10
Dependent Claim
193 words
A tool for determining the extent of defects in ferromagnetic tubing sections, comprising a continuous tubing string used in a subterranean well bore, at the wellhead as the tubing string travels into or out of the well bore, comprising: a fixed electrical conductor means traversely spaced from the tubing string and having a sinusoidally-shaped conductor cross-sectional distribution around the tubing string for applying a fluctuating magnetic field to a portion of the tubing string; detection means traversely spaced from the tubing string for detecting the driven field induced in the tubing string by the fluctuating magnetic field, the detection means including first and second coils each encircling the tubing string and having a sinusoidally-shaped conductor cross-sectional distribution and axially extending segments located at a plurality of spaced-apart locations around the periphery of the tubing string, the first coil having a sine conductor cross-sectional distribution and the second coil having a cosine conductor cross-sectional distribution; means for comparing a phase angle of the driven field; and means for correlating the difference between the phase angles of the fluctuating magnetic field and the driven field to determine the extent of defects in the tubing string.
Claim 11
Dependent Claim
24 words
The tool as defined in claim 8, wherein the detection means is spaced axially between the tubing string and the fixed electrical conductor means.
Claim 12
Dependent Claim
31 words
The tool as defined in claim 8, further comprising: a saturating DC drive coil for applying a saturated magnetic field to the tubing string in addition to the fluctuating magnetic field.
Claim 13
Dependent Claim
62 words
The tool as defined in claim 8, wherein the means for correlating comprises: signal processing means for amplifying signals from each of the first and second detector coils corresponding to an effective angular location on the element as a function of the conductor cross-sectional distribution of each of the detector coils to measure the extent of axially-extending defects in the tubing string.
Claim 14
Independent Claim
141 words
A method of determining the extent of axially-extending defect in an element during axial movement of the element, comprising the steps of: providing a fixed first coil having a sinusoidally-shaped conductor cross-sectional distribution around the element; providing a fixed second coil having sinusoidally-shaped conductor cross-sectional distribution of a different phase from the first coil; passing a sinusoidal electrical input through the fixed first coil for subjecting the element to a fluctuating magnetic field; passing a sinusoidal input through the second coil for cooperating with the first coil to subject the element to a substantially constant magnitude rotating magnetic field; and detecting the driven field induced in the axially moving element by the fluctuating magnetic field and detecting a change in phase between the driven fields and the fluctuating magnetic field to determine the extent of axially extending defects in the element.
Claim 15
Independent Claim
141 words
A method of determining the extent of axially-extending defect in an element during axial movement of the element, comprising the steps of: providing a fixed first coil having a sinusoidally-shaped conductor cross-sectional distribution around the element; providing a fixed second coil having sinusoidally-shaped conductor cross-sectional distribution of a different phase from the first coil; passing a sinusoidal electrical input through the fixed first coil for subjecting the element to a fluctuating magnetic field; passing a sinusoidal input through the second coil for cooperating with the first coil to subject the element to a substantially constant magnitude rotating magnetic field; and detecting the driven field induced in the axially moving element by the fluctuating magnetic field and detecting a change in phase between the driven fields and the fluctuating magnetic field to determine the extent of axially extending defects in the element.
Claim 16
Dependent Claim
26 words
The method as defined in claim 12, further comprising: subjecting the axially moving element to a saturated magnetic field in addition to the fluctuating magnetic field.
Claim 17
Dependent Claim
32 words
The method as defined in claim 12, wherein the driven field induced in the element by the fluctuating magnetic field is detected adjacent to and spaced from the periphery of the element.
Claim 18
Dependent Claim
31 words
The method as defined in claim 12, further comprising: detecting magnetic flux generated by the saturated magnetic field in the element to determine wall thickness variations in the axially moving element.
Claim 19
Dependent Claim
29 words
The method as defined in claim 15, further comprising: detecting flux leakage in the saturated magnetic field to measure the depth of local defects in the axially moving element.
Claim 20
Dependent Claim
26 words
The method as defined in claim 12, wherein the cross-sectional distribution of the first coil is offset 90° from the cross-sectional distribution of the second coil.
Claim 21
Dependent Claim
32 words
The method as defined in claim 17, wherein the sinusoidal electrical input pass through the first coil is offset 90° with respect to the sinusoidal electrical input passing through the second coil.
Claim 22
Dependent Claim
184 words
A tool for determining the extent of defects in ferromagnetic tubing sections, comprising a continuous tubing string used in a subterranean well bore, at the wellhead as the tubing string travels into or out of the well bore, comprising: a first fixed electrical conductor means traversely spaced from the tubing string and having a first sinusoidally-shaped conductor cross-sectional distribution around the tubing string for applying a fluctuating magnetic field to a portion of the tubing string; a second fixed electrical conductor means having a second sinusoidally-shaped conductor cross-sectional distribution around the element of a different phase from the first sinusoidally-shaped conductor distribution for applying the fluctuating magnetic field of a substantially constant magnitude; detection means traversely spaced from the tubing string for detecting the driven field induced in the tubing string by the fluctuating magnetic field; means for comparing a phase angle of the fluctuating magnetic field to a phase angle of the driven field; and means for correlating the difference between the phase angles of the fluctuating magnetic field and the driven field to determine the extent of defects in the tubing string.
Claim 23
Dependent Claim
184 words
A tool for determining the extent of defects in ferromagnetic tubing sections, comprising a continuous tubing string used in a subterranean well bore, at the wellhead as the tubing string travels into or out of the well bore, comprising: a first fixed electrical conductor means traversely spaced from the tubing string and having a first sinusoidally-shaped conductor cross-sectional distribution around the tubing string for applying a fluctuating magnetic field to a portion of the tubing string; a second fixed electrical conductor means having a second sinusoidally-shaped conductor cross-sectional distribution around the element of a different phase from the first sinusoidally-shaped conductor distribution for applying the fluctuating magnetic field of a substantially constant magnitude; detection means traversely spaced from the tubing string for detecting the driven field induced in the tubing string by the fluctuating magnetic field; means for comparing a phase angle of the fluctuating magnetic field to a phase angle of the driven field; and means for correlating the difference between the phase angles of the fluctuating magnetic field and the driven field to determine the extent of defects in the tubing string.
Claim 24
Dependent Claim
31 words
The tool as defined in claim 19, further comprising: a saturating DC drive coil for applying a saturated magnetic field to the tubing string in addition to the fluctuating magnetic field.
Claim 25
Dependent Claim
41 words
The tool as defined in claim 19, wherein the detection means comprises: first and second detector coils each encircling the tubing string and having axially extending segments located at a plurality of spaced-apart locations around the periphery of the tubing string.
Claim 26
Dependent Claim
39 words
The tool as defined in claim 21, wherein each of the detector coils has a sinusoidally-shaped conductor cross-sectional distribution, and the first coil has a sine conductor cross-sectional distribution and the second coil has a cosine conductor cross-sectional distribution.
Claim 27
Dependent Claim
62 words
The tool as defined in claim 22, wherein the means for correlating comprises: signal processing means for amplifying signals from each of the first and second detector coils corresponding to an effective angular location on the element as a function of the conductor cross-sectional distribution of each of the detector coils to measure the extent of axially-extending defects in the tubing string.
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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) | 1991-12-20 | 1992-06-20 | 1992-12-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-12-20 | 1996-06-20 | 1996-12-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-12-20 | 2000-06-20 | 2000-12-20 | $7700.00 | Window Closed / Lapsed |