Vertical magnetic field and its analytic signal applicability in oil field underground pipeline detection

We propose using the vertical component of the magnetic anomaly (vertical magnetic field (VMF)) and its analytic signal (AS) to detect oil field underground pipelines. The connection between two peaks of the VMF curves or the AS curves was used to calculate the pipeline azimuth, and the peak coordinates of the AS were used to determine the horizontal position of pipelines. Then, the effect of the pipeline magnetization direction and pipeline buried depth on the horizontal locating error was analyzed. Three typical pipeline models were used for verifying this method. Results indicate that this method can be used to precisely calculate the stretch direction of the pipeline and effectively improve the identification capability in detecting parallel pipelines. The horizontal position of the pipeline axis can be accurately located by the peak of the AS and the locating error increases with the increase in pipeline buried depth, but it is not affected by pipeline outer diameter, thickness, susceptibility. The instrument design and the VMF measurement strategy are realistic and applicable. The VMF detection with its AS provides a new effective method for horizontal locating and direction calculating of oil field underground pipelines.