Zhang Zhenyu1,2,3,4, Wang Gang2,3,4, Hu Xiangyun1, Li Yongbo2,3,4, Wang Dayong2,3,4, Yao Dawei2,3,4
1. China University of Geosciences(Wuhan), Wuhan, Hubei 430074, China;
2. Key Laboratory of Geophysical Electromagnetic Detection Technology, the Ministry of Land and Resources, Langfang, Hebei 065000, China;
3. Institute of Geophysical and Geochemical Exploration Technology, Chinese Academy of Geological Sciences, Langfang, Hebei 065000, China;
4. The Nation Center for Geological Exploration Technology, Langfang, Hebei 065000, China
Abstract：Nowadays controlled-source audio-frequency magnetotelluric method (CSAMT) carries out mainly scalar measurement,and this scalar CSAMT only produces a single direction current vector underground and calculates scalar impe-dance.It is only suitable for one-dimension targets or two-dimension targets in which structural trends are perpendicular to survey lines.For 3D complex structures,tensor measurement is proposed.In the paper,we use the meter V8 to carry out tensor CSAMT experiments.We record five component electrical and magnetic fields.For transmitters,we use two electrode current sources vertical each other.The impedance tensor decomposition technique is adopted at the data processing stage.The tensor CSAMT experiment results are compared with that of scalar CSAMT and audio-frequency magnetotelluric (AMT).According to the experiment results,tensor CSAMT data is generally coincident with AMT data,while AMT data are not so smooth due to its weak natural field signals.There is a big difference between scalar CSAMT and AMT data,so scalar CSAMT data cannot correctly reflect underground structures.Tensor CSAMT can overcome the scalar CSAMT limitations and AMT weak signals.Our research on tensor CSAMT may provide a good reference for petroleum geophysical exploration in the future.
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