Computational Method for Determining Subterranean Pipeline Direction Using Low-Frequency Current-Generated Magnetic Fields

One of the paramount responsibilities involves accurately ascertaining the orientation of subterranean hydrocarbon pipelines to prevent potential pipeline damage during geotechnical drilling and excavation activities, all the while ensuring the secure operation of the pipeline network. This paper introduces a technique for computing and establishing pipe orientation through the measurement of the magnetic field generated by subjecting the pipe to low-frequency electric current excitation. This approach incorporates various parameters, including the triaxial orthogonal magnetic field signal and the triaxial orthogonal gravity field component, all based on the magnetic effects of the electric current principle. To address the challenge posed by the variability in the alignment of the three-axis orthogonal magnetic flux gate and gravity acceleration sensor of the measuring instrument, three models are formulated to calculate pipeline orientation. Moreover, methods for selecting the appropriate model are furnished based on the symbols obtained from the measurement results. The reliability of the proposed calculation method is substantiated through empirical validation employing a custom-designed measurement apparatus. The maximum error across nine sets of experimental data stands at 4°, with an average error of 2.22°. The presented approach determines pipeline orientation within the entire detection range, irrespective of the measurement position, thus enhancing its adaptability.