A Method for Improving Detecting Accuracy of Locating Deeply Buried Refined Oil Pipelines

The highly accurate detecting technology of deeply refined oil pipelines has been used FDEM (frequency domain electromagnetic method) method in the subway shield construction site. We summary that how to improve detecting accuracy of refined oil pipelines for about 16 m buried depth. First step, we determine the direction Y of the target pipeline and narrow the searching area through detecting working of X direction on ground. With background interfere the error of pipeline's location is not acceptable and depth error is large when using two different working frequencies on ground detection. Second step, we need detect the direction Z of two boreholes with the distance at 5.0 m from target pipeline. And we can acquire H_z measured curve of the target pipeline nearby. Last step, measured and theoretical H_z curves is inverted and acquired high accurate results with location and depth is 20 cm and 10 cm. It can provide accurate and basic technical data for subway construction. The way of detecting Z direction of borehole can avoid the inference of X direction on ground and also provide a way to test the result of ground detecting. The method is worth popularizing to the acceptance of the quality of ground detection. The signal processing technology of detection dates will be widely used in detecting underground pipeline base on FDEM method with its powerful advance and superiority.