External penetrating rotating magnetic field detecting method for sucker rods

Abstract

The invention discloses an external penetrating rotating magnetic field detecting method for sucker rods. The detecting method comprises the following steps: a uniform rotating magnetic field generated by an excitation coil induces an annular eddy on the surface of a sample, and the annular eddy can be disturbed by defects at any angle on the sample; a detection coil picks up all axial disturbancesignals caused by the defects; voltage signals generated by the detection coil are amplified by a voltage amplifier and are received by a lock-in amplifier for processing, and real and imaginary voltage signals of defect signals are output; the signals are collected by a computer, and a variation curve is displayed on a front panel in real time by a LabVIEW program; and an impedance plan is drawnin MATLAB based on the real and imaginary data, and specific circumferential positions of the defects are judged according to image angles. The generated rotating magnetic field is more uniform and sensitive to the defects in all directions, so that all the axial disturbance signals generated by the defects can be picked up without being affected by lifting, and the method is suitable for the sucker rods with different outer diameters, and precise positions of the defects can be determined by a subsequent data processing method.

Description

technical field [0001] The invention belongs to the field of eddy current non-destructive testing, and relates to a wellhead detection method, in particular to a wellhead sucker rod detection method of an externally penetrating rotating magnetic field. Background technique [0002] In the petroleum industry, there are many methods of oil extraction, among which mechanical oil extraction is the most important, especially the rod pump, and the rod pumping technology occupies an important position in my country's oil extraction. Therefore, the sucker rod is an important tool in the process of oil well operation. A considerable part of the currently used sucker rods have been working for more than five years. Due to the harsh working conditions and long-term continuous repetitive service, the sucker rods are easily subjected to alternating, vibration and impact loads during use. Fatigue cracks occur. And because of the limited detection technology, equipment conditions and mai...

AI Technical Summary

Problems solved by technology

[0005] In the existing sucker rod wellhead detection technology, the detection signal of the eddy current detection technology is greatly affected by the lift-off effect. The ordinary eddy current detection probe has high requirements for scanning mechanical control, and generally has low efficiency and poor detection effect. Operators have high demands

The most important thing is that most of the current wellhead detection technologies are based on magnetic flux leakage detection technology, which can only detect defects perpendicular to the eddy current direction, and can only locate the defects in the axial direction, but cannot detect the circumferential position of the defects , the joint of the sucker rod cannot be detected

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