Magnetic Anomalies of Submarine Pipeline Based on Theoretical Calculation and Actual Measurement

• Published in: IEEE transactions on magnetics Vol. 55; no. 4; pp. 1 - 10
• Main Authors: Wang, Fangqi, Song, Yupeng, Dong, Lifeng, Tao, Changfei, Lin, Xubo
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.04.2019; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Correlation; Declination; Forward model; Gas pipelines; Geologic measurements; Geomagnetism; Magnetic anomalies; Magnetic domains; Magnetic methods; Magnetic permeability; Magnetism; Magnetization; Magnetometers; Natural gas; Parameters; Pipelines; remanent magnetization; Sea measurements; submarine pipeline; total-field magnetic anomaly (TMA); Underwater pipelines; Underwater structures; Underwater vehicles
• ISSN: 0018-9464; 1941-0069
• DOI: 10.1109/TMAG.2019.2898951

Marine magnetic method is widely used for detecting and locating the submarine pipeline. In this paper, the theoretical calculation model of total-field magnetic anomalies (TMAs) of submarine pipeline was derived based on Poisson's equation. Taking a submarine gas pipeline for example, the TMA theoretical calculation and the verification sea test were carried out. Based on the calculation, the influences that the geomagnetic parameters, pipeline parameters, and measuring plane height had on the TMA characteristics of pipeline were analyzed. The TMA shape changed slightly with geomagnetic declination <inline-formula> <tex-math notation="LaTeX">{D} </tex-math></inline-formula> and was significantly influenced by the azimuth <inline-formula> <tex-math notation="LaTeX">\theta </tex-math></inline-formula> of the pipeline. The corresponded location of the pipeline on the TMA profile varied with <inline-formula> <tex-math notation="LaTeX">{D} </tex-math></inline-formula> seemed to be symmetrical with <inline-formula> <tex-math notation="LaTeX">{D} = 0^\circ </tex-math></inline-formula> as the center, but within 1.0 m, and changed greatly with <inline-formula> <tex-math notation="LaTeX">\theta </tex-math></inline-formula> with an offset distance of upping to 4.4 m. The TMA amplitude was linearly positively correlated with geomagnetic intensity <inline-formula> <tex-math notation="LaTeX">{T} _{0} </tex-math></inline-formula>, quadratic difference of outer and inner diameters of pipeline <inline-formula> <tex-math notation="LaTeX">{d} _{1}^{2} </tex-math></inline-formula>-<inline-formula> <tex-math notation="LaTeX">{d} _{2}^{2} </tex-math></inline-formula>, and susceptibility <inline-formula> <tex-math notation="LaTeX">\kappa </tex-math></inline-formula>, respectively, and was inversely proportional to the square of measuring plane height <inline-formula> <tex-math notation="LaTeX">{R} </tex-math></inline-formula>, and changed greatly with <inline-formula> <tex-math notation="LaTeX">{D} </tex-math></inline-formula>, <inline-formula> <tex-math notation="LaTeX">{I} </tex-math></inline-formula>, and <inline-formula> <tex-math notation="LaTeX">\theta </tex-math></inline-formula> but without obvious correlation. The TMA width changed greatly with <inline-formula> <tex-math notation="LaTeX">{I} </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">\theta </tex-math></inline-formula>, respectively, but without obvious correlation, and was approximately positively correlated with R. On the TMA profile that was perpendicular to the pipeline, there would be an obvious "pulse" anomaly on the smooth profile, and the location of pipeline corresponded a specific point near the TMA maximum point depending on <inline-formula> <tex-math notation="LaTeX">{D} </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">\theta </tex-math></inline-formula>, so that the accurate location of the pipeline needed to be corrected according to these two parameters, not just the TMA maximum point.