| 摘要 |
A system for detecting defects in a string being pulled from the well inc ludes an AC exciter (14) to induce eddy currents in the string, and a plural ity of magnetic flux leakage detectors (16) circumferentially spaced about t he string, each for detecting magnetic flux leakage indicative of a defect. Magnetic flux leakage signals may be output to computer (32) at the well sit e, or may be transmitted to another computer (36) remote from the well site. Data may be displayed as a function of depth of the string in the well, and signals may be calibrated to enhance reliability.
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