Application of 2D inversion of magnetotelluric data bearing terrain information based on an unstructured mesh

JIANG Fen-Yong; YE Yi-Xin; CHEN Hai-Wen; YANG Shuo-Jian

doi:10.11720/wtyht.2022.1397

2022 Vol. 46, No. 2

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JIANG Fen-Yong, YE Yi-Xin, CHEN Hai-Wen, YANG Shuo-Jian. 2022. Application of 2D inversion of magnetotelluric data bearing terrain information based on an unstructured mesh. Geophysical and Geochemical Exploration, 46(2): 482-489. doi: 10.11720/wtyht.2022.1397

Citation:

JIANG Fen-Yong, YE Yi-Xin, CHEN Hai-Wen, YANG Shuo-Jian. 2022. Application of 2D inversion of magnetotelluric data bearing terrain information based on an unstructured mesh. Geophysical and Geochemical Exploration, 46(2): 482-489. doi: 10.11720/wtyht.2022.1397

Application of 2D inversion of magnetotelluric data bearing terrain information based on an unstructured mesh

School of Geophysics and Measurement-Control Technology, East China University of Technology,Nanchang 330013,China

Received Date: 16 July 2021

Publish Date: 28 June 2022

Abstract

Abstract

This paper focuses on the application of the 2D inversion of magnetotelluric data that bear terrain information based on an unstructured adaptive triangular mesh. An adaptive unstructured triangular grid can be used to accurately simulate undulating terrain and complex geological structures. The adaptive unstructured triangular grids for magnetotelluric forward modeling are automatically refined using the a posteriori error estimation with the finite element solution, which ensures the accuracy of the model response. As for adaptive unstructured triangular grids for magnetotelluric inversion, fine mesh generation is adopted for the inversion target areas, while coarse grid generation is utilized for the boundary areas of the model, thus reducing unnecessary inversion parameters on the premise of satisfying the inversion accuracy. According to the inversion of an undulating-terrain model of land and an undulating-seabed model, the accuracy and applicability of the algorithm are verified and the algorithm can be used to image the multi-scale structures under the undulating terrain of land and seabed. Then, the method was applied to the inversion of the measured data of the Houshan area in Karamay. As a result, the resistivity structure obtained through the inversion was consistent with the geological data and the results obtained through the nonlinear conjugate gradient inversion.
- unstructured mesh /
- MT /
- 2D inversion /
- terrain /
- Karamay

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References

[1]	Huang X Y, Deng J Z, Chen X, et al. Magnetotelluric extremum boundary inversion based on different stabilizers and its application in a high radioactive waste repository site selection[J]. Applied Geophysics, 2019, 16(3) : 367-377. Google Scholar
[2]	李磊. 湘南骑田岭锡铅锌多金属矿区岩矿石电性研究[J]. 物探与化探, 2007(S1) : 77-80,93. Google Scholar
[3]	Li L. Researchs on rock electrical properties in the Qittianling,lead and zinc polymetallic ore deposit,southern HuNan[J]. Geophysical and Geochemical Exploration, 2007(S1) : 77-80,93. Google Scholar
[4]	熊彬, 罗天涯, 蔡红柱, 等. 起伏地形大地电磁二维反演[J]. 物探与化探, 2016, 40(3):587-593. Google Scholar
[5]	Xiong B, Luo T Y, Cai H Z, et al. Two-dimensional magnetotelluric inversion of undulating terrain[J]. Geophysical and Geochemical Exploration, 2016, 40(3): 587-593. Google Scholar
[6]	Alan G J. Distortion decomposition of the magnetotelluric impedance tensors from a one-dimensional anisotropic Earth[J]. Geophysical Journal International, 2012, 189(1): 268-284. Google Scholar
[7]	Juanjo L, Pilar Q, Jaume P. Effects of galvanic distortion on magnetotelluric data over a three-dimensional regional structure[J]. Geophysical Journal International, 1998(2) : 295-301. Google Scholar
[8]	Franke A, Borner R, Spitzer K, et al. Adaptive unstructured grid finite element simulation of two-dimensional magnetotelluric fields for arbitrary surface and seafloor topography[J]. Geophysical Journal International, 2007, 171(1) : 71-86. Google Scholar
[9]	Shewchuk J R. Delaunay refinement algorithms for triangular mesh generation[J]. Computational Geometry Theory & Applications, 2002, 47(1-3) : 741-778. Google Scholar
[10]	Cao X Y, Yin C C, Zhang B, et al. 3D magnetotelluric inversions with unstructured finite-element and limited-memory quasi-Newton methods[J]. Chinese Geophysical Society, 2018, 15(3) : 556-565. Google Scholar
[11]	惠哲剑, 殷长春, 刘云鹤, 等. 基于非结构有限元的时间域海洋电磁三维反演[J]. 地球物理学报, 2020, 63(8) : 3167-3179. Google Scholar
[12]	Hui Z J, Yin C C, Liu Y H, et al. 3D inversion of time-domain marine CSEM based on unstructured finite element method[J]. Chinese Journal of Geophysics, 2020, 63(8) : 3167-3179. Google Scholar
[13]	Kerry K, Chester W. Adaptive finite-element modeling using unstructured grids: The 2D magnetotelluric example[J]. Society of Exploration Geophysicists, 2006, 71(6) : G291-G299. Google Scholar
[14]	Li Y G, Key K. 2D marine controlled-source electromagnetic modeling: Part 1 — An adaptive finite-element algorithm[J]. Geophysics, 2007, 72(2) : WA51. Google Scholar
[15]	Li Y G, Josef P, et al. Adaptive finite element modelling of two-dimensional magnetotelluric fields in general anisotropic media[J]. Geophysical Journal International, 2008, 175(3) : 942-954. Google Scholar
[16]	刘颖, 李予国, 韩波. 可控源电磁场三维自适应矢量有限元正演模拟[J]. 地球物理学报, 2017, 60(12) : 4874-4886. Google Scholar
[17]	Liu Y, Li Y G, Han B. Adaptive edge finite element modeling of the 3D CSEM field on unstructured grids[J]. Chinese Journal of Geophysics, 2017, 60(12) : 4874-4886. Google Scholar
[18]	Ovall J S. Asymptotically exact functional error estimators based on superconvergent gradient recovery[J]. Numerische Mathematik, 2006, 102(3) : 543-558. Google Scholar
[19]	Key K, Ovall J. A parallel goal-oriented adaptive finite element method for 2.5D electromagnetic modelling[J]. Geophysical Journal International, 2011. 186(1) : 137-154. Google Scholar
[20]	韩骑, 胡祥云, 程正璞, 等. 自适应非结构有限元MT二维起伏地形正反演研究[J]. 地球物理学报, 2015, 58(12) : 4675-4684. Google Scholar
[21]	Han Q, Hu X Y, Chen Z P, et al. A study of two dimensional MT inversion with steep topography using the adaptive unstructured finite element method[J]. Chinese Journal of Geophysics, 2015, 58(12) : 4675-4684. Google Scholar
[22]	Key K. MARE2DEM: A 2D inversion code for controlled-source electromagnetic and magnetotelluric data[J]. Geophysical Journal International, 2016, 207(1) : 571-588. Google Scholar
[23]	Constable S C, Parker R L, Constable C G. Occam's inversion:A practical algorithm for generating smooth models from electromagnetic sounding data[J]. Geophysics, 1987, 52(3) : 289-300. Google Scholar
[24]	何梅兴, 胡祥云, 叶益信, 等. 2.5维可控源音频大地电磁法Occam反演理论及应用[J]. 地球物理学进展, 2011, 26(6) : 2163-2170. Google Scholar
[25]	He M X, Hu X Y, Ye Y X, et al. 2.5D controlled source audio-frequency magnetotellurics occam inversion[J]. Progress in Geophysics, 2011, 26(6) : 2163-2170. Google Scholar
[26]	熊彬, 罗延钟, 强建科. 瞬变电磁2.5维反演中灵敏度矩阵计算方法(Ⅰ)[J]. 地球物理学进展, 2004, 19(3) : 616-620. Google Scholar
[27]	Xiong B, Luo Y Z, Qiang J K. Methods for calculating sensitivities for 2.5D transient electromagnetic inversion[J]. Progress in Geophysics, 2004, 19(3) : 616-620. Google Scholar
[28]	Farquharson C G, Oldenburg D W. Approximate sensitivities for the electromagnetic inverse problem[J]. Geophysical Journal International, 1996, 126(1) : 235-252. Google Scholar
[29]	Mcgillivray P R, Oldenburg D W, Ellis R G, et al. Calculation of sensitivities for the frequency-domain electromagnetic problem[J]. Geophysical Journal International, 1994, 116(1) : 1-4. Google Scholar
[30]	Parker R L. Geophysical inverse theory[M]. Princeton: Princeton University Press, 1994. Google Scholar
[31]	Zhdanov M S. Inverse theory and applications in geophysics[M]. New York: Elsevier, 2002. Google Scholar