Spectral characteristics of the digital filter for electromagnetic field decomposition in 3D MCSEM
Wang Shu-Ming, Di Qing-Yun,*, Xiao Yun-xin, Fang Qi-chao, Li De-shan
1. Institute of Geophysics and Geomatics, China University of Geosciences, Hubei Subsurface Multi-scale Imaging Key Laboratory, No. 388, Lumo Rd., Wuhan, Hubei 430074, China.
2. Institute of Geology and Geophysics, Chinese Academy of Sciences, No.19 Beitucheng Rd., Chaoyang Dist., Beijing 100029, China.
3. Xi’an Research Institute of China Coal Technology & Engineering Group Corporation, No.82 Jinyeyi Rd., Xian, Shaanxi 710054, China.
Abstract The data of marine-controlled source electromagnetic exploration collected in shallow waters are considerably influenced by airwaves. Thus, finding ways to eliminate this influence is important. Decomposing the electromagnetic fi eld into the upgoing and downgoing fields is an effective method to resolve this problem. By utilizing the Stratton–Chu integral transform, this study proposes a novel method that can separate a 3D electromagnetic field into upgoing and downgoing electromagnetic fields through rigorous mathematical deduction. We examine the spectral characteristics to determine the eff ectiveness of the method. The results show that a practical digital fi lter can be achieved by selecting a reasonable window size and spatial step, as demonstrated through spectral comparisons with an analytical filter.
2025, Vol. 22 
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