| 摘要 |
A system for detecting defects in a string being pulled from the well includes an AC exciter (14) to induce eddy currents in the string, and a plurality of magnetic flux leakage detectors (16) circumferentially spaced about the string, each for detecting magnetic flux leakage indicative of a defect. Magnetic flux leakage signals may be output to computer (32) at the well site, 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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