A new pulsed eddy current (PEC) - electromagnetic (EM) based tool called the enhanced Pipe-thickness Detection Tool (ePDT) has been introduced for multiple pipes’ corrosion inspection. The tool can measure the metal wall thickness of five concentric pipes with the maximum outer diameter (OD) up to 26". This capability and ePDT's unique configuration provide the most advanced downhole solution for tubular evaluations of production, injector and gas/oil storage wells. The ePDT features a 2" (51mm) OD with ratings of 350°F (175°C) and 20,000 psi (138Mpa).

The innovative sensor of ePDT incorporates: (1) A fractal transmitter (TX) coil array that improves the tool's performances with enhanced signal-to-noise ratio (SNR) covering a wide signal dynamic range, and adaptability for various logging speeds and spatial resolutions for varying pipes; (2) A synthetic aperture of the receiver (RX) coil array for noise compensation from extraneous tool motion; (3) A wide-spatial aperture RX coil array which when combined with (1) and (2) allows for compressing the inner pipe remnant magnetization interferences without sacrificing spatial resolution; (4) A "shallow" measuring transducer to detect EM properties for logging data corrections.

The results from lab tests and field trials combined with simulation indicate that the ePDT can quantitatively measure 5 pipes from 2-7/8" as the smallest tubing to the maximum outer casing with the OD of 26". In addition, the logging speed can be significantly increased compared to previous generation tools.

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