An automatic system measuring electromagnetic parameters for oil field pipes

The fault detection and diagnosis of oil field pipes are very important to the petroleum companies, as if known, the fault of steel products can be detected based on the eddy current technique. The depth of a defect on an oil field pipe will determine the change in amplitude and phase of the detected signal. However, this signal is also affected by electromagnetic parameters in the vicinity of the fault. It is impossible, therefore, to accurately interpret the severity of the fault from a detected signal, without the knowledge of electromagnetic parameters. A system which can automatically measure electromagnetic parameters of oil field pipes has been developed, so that the correct interpretation of a pipe defect can be provided. An electronic emulator was built for differentiating the permeability of pipes accurately. The electronic emulator takes the signal from the transmission circuit, and converts it to the compensation signal with a certain amplitude and phase shift according to presettings. The combined received signal and compensation signal are conditioned and compared with the transmitted signal to give the expanded phase shift signal at the output. To stand the rigorous working condition in the underground pipes, the system is made capable of working at high temperature. Also taken into account is the variation of the internal diameter and the wall thickness of casing pipes, which affect the measurement of electromagnetic parameters. Therefore, the system can provide high sensitivity electromagnetic parameters for interpreting various types of defects in oil field pipes.<<ETX>>