Method and apparatus for measuring axially extending defects in ferromagnetic elements
AssigneePA Incorporated
InventorsClive C. Lam, Marvin Milewits, James E. Bradfield
Life of this patent
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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.
Claims23
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.
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.
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.
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.
Dependencies are inferred from the claim text.