Journal of Jilin University(Earth Science Edition) ›› 2018, Vol. 48 ›› Issue (6): 1845-1853.doi: 10.13278/j.cnki.jjuese.20170220

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3-D Arbitrarily Anisotropic Modeling for Towed Marine DC Resistivity Method in Deep Ocean

Yang Zhilong, Yin Changchun, Zhang Bo, Liu Yunhe, Ren Xiuyan, Hui Zhejian   

  1. College of GeoExploration Science and Technology, Jilin University, Changchun 130026, China
  • Received:2017-09-01 Published:2018-11-26
  • Supported by:
    Supported by National Nature Science Foundation of China (41530320, 41774125) and Key National Research Project of China (2016YFC0303100, 2017YFC0601900)

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Abstract: Deep-sea exploration with high precision is one of the research focuses in marine exploration. The traditional exploration by using a towed transmitter in seawater while positioning receiver at seafloor has the defects that the receivers can easily get lost, the data are instable, and the survey electrodes are influenced by ocean topography. In order to solve these problems, we designed an exploration technique with high working efficiency,reliability and low exploration cost, and developed a 3D DC forward modelling algorithm for accurately recognizing the electric characteristics of the sediment and mineral sources. Based on the previous researches, we put forwarded a towed marine DC resistivity method, and presented a 3D anisotropic forward modelling algorithm for deep-sea DC resistivity method by using finite-elements on unstructured grids for a fully towed DC system with considering the anisotropy of sea sediments at the ocean bottom. We checked the accuracy of our algorithm against 1D semi-analytical solutions for an arbitrarily anisotropic sea bottom. Through the numerical experiment analyses on typical anisotropic models, we demonstrated the high resolution of DC resistivity to the anisotropy of seafloor sediments and minerals. Based on these simulations, we summarized the characteristics of the apparent resistivity when the axis of the anisotropic conductivity rotted around the Descartes coordinate axis, and discussed the influence of the submarine topography on the anisotropic explorations.

Key words: DC resistivity method, towed deep-sea exploration, unstructured finite-element, electrical anisotropy

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