3-D Full-Wave Inversion of Helicopter Transient Electromagnetic Data in Frequency Domain

• Published in: IEEE transactions on geoscience and remote sensing Vol. 58; no. 7; pp. 4928 - 4938
• Main Authors: Qiu, Chen, Liang, Bingyang, Han, Feng, Li, Jutao, Fang, Guangyou, Liu, Qing Huo
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.07.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithms; Anomalies; Coils; Conductivity; Data; Drilling; Electric fields; Electric-field integral equation (EFIE); Electromagnetic radiation; Flight; Frequency domain analysis; frequency-domain inversion; helicopter transient electromagnetics (HTEM); Helicopters; Integral equations; Inverse scattering; Inversion; Iterative methods; Magnetic field; Magnetic fields; nomogram; Nomograms; Profiles; Receivers; Reconstruction; Surveys; Time-domain analysis; Transmitters
• ISSN: 0196-2892; 1558-0644
• DOI: 10.1109/TGRS.2020.2968804

Helicopter transient airborne electromagnetics (HTEM) has become a useful tool in mineral explorations and geological or environmental detection in recent decades. This article presents the frequency-domain 3-D full-wave inversion of the electromagnetic data recorded by a newly built HTEM system. In the forward process, the secondary magnetic field is calculated through the volume electric-field integral equation (EFIE). In the inversion process, the secondary field is first extracted from the total field measured by the HTEM system. Then the Born iterative method (BIM) is adopted to solve the nonlinear inverse scattering problem for the 3-D reconstruction of conductivity. It is first applied to the synthetic models to verify their effectiveness and accuracy. The effects of adjacent underground anomalies on the 3-D inversion performed in a local region within the long flight lines are studied and discussed. Then the BIM solver is used to invert for the underground anomalies using the field measured data recorded by the newly built HTEM system. The 2-D slices from the reconstruction are compared with the nomogram. It is found that the locations of the high-conductivity regions in the BIM results are consistent with locations of the peaks in the nomogram. The reconstructed profiles are also compared with the drilling data obtained near one flight line. The good agreement shows that the 3-D BIM inversion algorithm can be used to reconstruct the underground ore in HTEM surveys.