Pseudo-2D MT inversion technique for small-frame TEM and its application in advance geological prediction

Authors

HAN Ziqiang, Engineer School, Qinghai Institute of Technology, Xining 810016, ChinaFollow
WANMA Longzhi, Engineer School, Qinghai Institute of Technology, Xining 810016, China
LI Xiangfeng, School of Civil and Hydraulic Engineering, Qinghai University, Xining 810016, China
YANG Yongqiang, Engineer School, Qinghai Institute of Technology, Xining 810016, China
ZHU Xiaoming, Gansu Province Transportation Planning Survey & Design Institute Co., Ltd., Lanzhou 730030, China
LUO Chengxian, Gansu Province Transportation Planning Survey & Design Institute Co., Ltd., Lanzhou 730030, China
TANG Li, Engineer School, Qinghai Institute of Technology, Xining 810016, ChinaFollow

Abstract

Objective To address the bottlenecks of low computational efficiency and impracticality of multi-dimensional inversion in the advance geological prediction based on the transient electromagnetic method (TEM), this study developed a pseudo-two-dimensional (2D) magnetotelluric (MT) inversion technique for small-frame TEM based on time-frequency transformation. Methods First, this study corroborated the significant similarity between the late-time apparent resistivity derived using small-frame TEM and the Cagniard apparent resistivity in the MT method under the parameters commonly used in advance geological prediction. Then, the optimal time-frequency transformation coefficient (C_TF) was introduced to achieve a rapid conversion from the late-time apparent resistivity to the Cagniard apparent resistivity. The maximum average conversion deviation was determined at 3.7%, suggesting generally small deviations. Last, a mature MT inversion method was employed to process the converted data.Results In the pseudo-1D MT inversion results, the maximum relative resistivity and depth errors were determined at 6.14% and 5.73%, respectively, suggesting generally small inversion errors. In the pseudo-2D MT inversion results, the inversion results derived from survey lines above the water-bearing structure reflected the boundary locations and actual depth of the water-bearing structure, and the inverted resistivity approximated to the actual resistivity of the water-bearing structure. In contrast, the inversion results obtained using survey lines outside the water-bearing structure can reflect the presence of the low-resistivity water-bearing structure. However, certain deviations were observed between the specific inversion parameters and their actual values. Conclusions This method takes less than 20 minutes to calculate on a common PC, which improves the calculation efficiency and prediction accuracy, and provides a new practical 2D inversion approach for TEM advanced geological prediction.

Keywords

transient electromagnetic method (TEM), small-frame source, magnetotellurics (MT), advance geological prediction, 2D inversion, time-frequency transformation, Cagniard apparent resistivity

DOI

10.12363/issn.1001-1986.24.11.0686

Recommended Citation

HAN Ziqiang, WANMA Longzhi, LI Xiangfeng, et al. (2025) "Pseudo-2D MT inversion technique for small-frame TEM and its application in advance geological prediction," Coal Geology & Exploration: Vol. 53: Iss. 8, Article 18.
DOI: 10.12363/issn.1001-1986.24.11.0686
Available at: https://cge.researchcommons.org/journal/vol53/iss8/18

Reference

[1] 张继锋，孙乃泉，刘最亮，等. 电磁法在煤矿水害隐患探测方面的综述[J]. 煤田地质与勘探，2023，51(2)：301−316.

ZHANG Jifeng，SUN Naiquan，LIU Zuiliang，et al. Electromagnetic methods in the detection of water hazards in coal mines：A review[J]. Coal Geology & Exploration，2023，51(2)：301−316.

[2] 曾一凡，武强，赵苏启，等. 我国煤矿水害事故特征、致因与防治对策[J]. 煤炭科学技术，2023，51(7)：1−14.

ZENG Yifan，WU Qiang，ZHAO Suqi，et al. Characteristics，causes，and prevention measures of coal mine water hazard accidents in China[J]. Coal Science and Technology，2023，51(7)：1−14.

[3] 孙文洁，李文杰，宁殿艳，等. 我国煤矿水害事故现状、预测及防治建议[J]. 煤田地质与勘探，2023，51(12)：185−194.

SUN Wenjie，LI Wenjie，NING Dianyan，et al. Current states，prediction and prevention suggestions for water hazard accidents in China’s coal mines[J]. Coal Geology & Exploration，2023，51(12)：185−194.

[4] 葛颜慧，李术才，张庆松，等. 基于风险评价的岩溶隧道综合超前地质预报技术研究[J]. 岩土工程学报，2010，32(7)：1124−1130.

GE Yanhui，LI Shucai，ZHANG Qingsong，et al. Comprehensive geological prediction based on risk evaluation during tunneling in karst area[J]. Chinese Journal of Geotechnical Engineering，2010，32(7)：1124−1130.

[5] 王朋朋，张勇，许帆，等. 深长向斜隧道涌突水综合预报技术及应用[J]. 公路，2019，64(5)：297−301.

[6] ZHU Hehua，YAN Jinxiu，LIANG Wenhao. Challenges and development prospects of ultra–long and ultra–deep mountain tunnels[J]. Engineering，2019，5(3)：384−392.

[7] 武军杰. 瞬变电磁新技术在隧道超前地质预报中的应用研究[D]. 西安：长安大学，2005.

WU Junjie. Application research of transient electromagnetic new technology in advanced geological predicition of tunnels[D]. Xi’an：Chang’an University，2005.

[8] 沈福斌，黄倩，刘向辉，等. 矿井瞬变电磁探测技术及综合应用研究[J]. 陕西煤炭，2017，36(4)：17−20.

SHEN Fubin，HUANG Qian，LIU Xianghui，et al. Research on the mine transient electromagnetic detectiontechnology and its comprehensive application[J]. Shaanxi Coal，2017，36(4)：17−20.

[9] TARTARAS E，ZHDANOV M S，WADA K，et al. Fast imaging of TDEM data based on S–inversion[J]. Journal of Applied Geophysics，2000，43(1)：15−32.

[10] 薛国强，李貅，底青云. 瞬变电磁法正反演问题研究进展[J]. 地球物理学进展，2008，23(4)：1165−1172.

XUE Guoqiang，LI Xiu，DI Qingyun. Research progress in TEM forward modeling and inversion calculation[J]. Progress in Geophysics，2008，23(4)：1165−1172.

[11] LEE K H，LIU G，MORRISON H F. A new approach to modeling the electromagnetic response of conductive media[J]. Geophysics，1989，54(9)：1180−1192.

[12] GERSHENSON M. Simple interpretation of time–domain electromagnetic sounding using similarities between wave and diffusion propagation[J]. Geophysics，1997，62(3)：763−774.

[13] 杨云见，王绪本，何展翔. 考虑关断时间效应的瞬变电磁一维反演[J]. 物探与化探，2005，29(3)：234−236.

YANG Yunjian，WANG Xuben，HE Zhanxiang. 1D inversion of transient electromagnetic data in consideration of ramp time effect[J]. Geophysical and Geochemical Exploration，2005，29(3)：234−236.

[14] 张继令，翁爱华. 中心回线瞬变电磁测深一维Occam反演[J]. 铁道勘察，2007，33(2)：40−43.

ZHANG Jiling，WENG Aihua. Inversion display of Occam used in in–loop transient electromagnetic sounding[J]. Railway Investigation and Surveying，2007，33(2)：40−43.

[15] 智庆全，武军杰，邓晓红，等. 地下瞬变电磁法一维反演[J]. 物探化探计算技术，2015，37(5)：566−570.

ZHI Qingquan，WU Junjie，DENG Xiaohong，et al. The one–dimension inversion of underground transient electromagnetic data[J]. Computing Techniques for Geophysical and Geochemical Exploration，2015，37(5)：566−570.

[16] 李大俊. 基于时频变换实现矩形大定源瞬变电磁数据三维频率域反演[D]. 长春：吉林大学，2017.

LI Dajun. Three–dimensional frequency–domain inversion of transient electromagnetic data from a rectanglar large loop based on time–frequency transformation method[D]. Changchun：Jilin University，2017.

[17] YANG Yunjian，WANG Xuben，LIU Xuejun，et al. A three–dimensional transient electromagnetic data inversion method based on a time–frequency transformation[J]. Applied Geophysics，2020，17(3)：361−376.

[18] 齐彦福，智庆全，李貅，等. 考虑关断时间的地面瞬变电磁三维带地形反演[J]. 地球物理学报，2021，64(7)：2566−2577.

QI Yanfu，ZHI Qingquan，LI Xiu，et al. Three–dimensional ground TEM inversion over a topographic earth considering ramp time[J]. Chinese Journal of Geophysics，2021，64(7)：2566−2577.

[19] 柳尚斌. 基于后推欧拉与直接分解的瞬变电磁三维高效正演方法及L–BFGS三维反演[D]. 济南：山东大学，2022.

LIU Shangbin. Efficient 3D forward modeling method and L–BFGS inversion for transient electromagnetic based on backward Euler and direct–spliting scheme[D]. Jinan：Shandong University，2022.

[20] 李创社，张彦鹏，李实，等. 瞬变电磁勘探中的人工神经网络反演法[J]. 西安交通大学学报，2001，35(6)：604−607.

LI Chuangshe，ZHANG Yanpeng，LI Shi，et al. New inversion method of artificial neural network in transient electromagnetic inversion[J]. Journal of Xi’an Jiaotong University，2001，35(6)：604−607.

[21] 李明星，肖林通，张倚瑞，等. 瞬变电磁粒子群优化反演研究[J]. 煤炭技术，2014，33(9)：302−304.

LI Mingxing，XIAO Lintong，ZHANG Yirui，et al. Research on particle swarm optimization inversion of transient electromagnetic method[J]. Coal Technology，2014，33(9)：302−304.

[22] 李锋平，杨海燕，刘旭华，等. 瞬变电磁反演中的非线性规划遗传算法[J]. 物探与化探，2017，41(2)：347−353.

LI Fengping，YANG Haiyan，LIU Xuhua，et al. Nonlinear programming genetic algorithm in transient electromagnetic inversion[J]. Geophysical and Geochemical Exploration，2017，41(2)：347−353.

[23] 司元雷，郑龙金. 基于遗传退火进化算法的瞬变电磁非线性反演[J]. 计算机应用与软件，2020，37(11)：172−177.

SI Yuanlei，ZHENG Longjin. Transient electromagnetic nonlinear inversion based on genetic annealing evolutionary algorithm[J]. Computer Applications and Software，2020，37(11)：172−177.

[24] 李瑞友，白细民，张勇，等. 基于小波包分解与GA优化BP神经网络的瞬变电磁反演[J]. 吉林大学学报(地球科学版)，2024，54(3)：1003−1015.

LI Ruiyou，BAI Ximin，ZHANG Yong，et al. Using wavelet packet denoising and BP neural network based on GA optimization for transient electromagnetic inversion[J]. Journal of Jilin University (Earth Science Edition)，2024，54(3)：1003−1015.

[25] 韩自强. 用于大回线源瞬变电磁场一维正演计算的两种方法对比[J]. 地球物理学进展，2016，31(3)：1103−1110.

HAN Ziqiang. Two calculation methods comparison for 1D large loop source transient electromagnetic field forward[J]. Progress in Geophysics，2016，31(3)：1103−1110.

[26] 余友. 电磁测深中极值的研究及其应用[D]. 长沙：中南大学，2012.

YU You. Research and application of extreme in the electromagnetic sounding[D]. Changsha：Central South University，2012.

[27] 李金铭. 地电场与电法勘探[M]. 北京：地质出版社，2005.

[28] 薛国强，李貅，郭文波，等. 从瞬变电磁测深数据到平面电磁波场数据的等效转换[J]. 地球物理学报，2006，49(5)：1539−1545.

XUE Guoqiang，LI Xiu，GUO Wenbo，et al. Equivalent transformation from TEM field sounding data to plane–wave electromagnetic sounding data[J]. Chinese Journal of Geophysics，2006，49(5)：1539−1545.

[29] STERNBERG B K，WASHBURNE J C，PELLERIN L. Correction for the static shift in magnetotellurics using transient electromagnetic soundings[J]. Geophysics，1988，53(11)：1459−1468.

[30] 陈明生. 关于频率电磁测深几个问题的探讨(八)：频率电磁测深与瞬变电磁测深的关系[J]. 煤田地质与勘探，2015，43(1)：81−85.

CHEN Mingsheng. On the relationship between the frequency electromagnetic sounding with the transient electromagnetic sounding[J]. Coal Geology & Exploration，2015，43(1)：81−85.

[31] 张文昊. 弗雷歇距离判断曲线相似度的嵌入式模块[J]. 单片机与嵌入式系统应用，2020，20(9)：17−20.

ZHANG Wenhao. Embedded module of curve similarity judging based on Fréchet distance[J]. Microcontrollers & Embedded Systems，2020，20(9)：17−20.

[32] 何继善，吴小平，柳建新，等. 利用小波变换确定电磁测深曲线拐点的应用研究[J]. 物探化探计算技术，2005，27(3)：219−222.

HE Jishan，WU Xiaoping，LIU Jianxin，et al. The application research of the inflection point ascertaining of electromagnetic sounding curve using wavelet transform[J]. Computing Techniques for Geophysical and Geochemical Exploration，2005，27(3)：219−222.

[33] 孙怀凤. 隧道含水构造三维瞬变电磁场响应特征及突水灾害源预报研究[D]. 济南：山东大学，2013.

SUN Huaifeng. Three–dimensional transient electromagnetic responses of water bearing structures in tunnels and prediction of water inrush sources[D]. Jinan：Shandong University，2013.

[34] 陈小斌，赵国泽. 自动构建大地电磁二维反演的测点中心网格[J]. 地球物理学报，2009，52(6)：1564−1572.

CHEN Xiaobin，ZHAO Guoze. Automatic construction of a site–centered grid (SCG) for 2D magnetotelluric inversion[J]. Chinese Journal of Geophysics，2009，52(6)：1564−1572.