SNR Improvement for Drill Pipe Leakage Flux Testing Signals by Using Magnetic Shielding Effect

Magnetic flux leakage(MFL) technique is generally considered to be an efficient and effective non-destructive testing(NDT) method and has been widely used in the oil field inspection industry for the examination of drill pipe. Electromagnetic finite element analysis shows that pipe magnetic flux leakage signals are centralized near defects obviously when the magnetic shielding exists. At this time, the background magnetic flux between permanent magnet components through the air coupling shall be reduced greatly. Drill pipe magnetic flux leakage testing confirms the analysis results, and the probe with magnetic shielding device can improve SNR of the magnetic flux leakage signals obviously. Thus, it is helpful to improve pipe leakage flux testing sensitivity.