全波形时域航空电磁数据的计算及其在电磁探测中的应用（英文）
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摘要
航空瞬变电磁法具有探测效率高、电磁异常分辨率高等优点,尤其适用于深部矿产及老矿区周边的资源探测。本文模拟了全波形航空电磁数据,结合数值研究的结果,通过实验验证了关断期间段电磁响应在异常探测中的优势。首先,基于吉林大学研制的航空瞬变电磁系统(JLU-ATEM~Ⅰ型),采用时域有限差分方法和卷积算法计算了三维模型的全波形航空瞬变电磁响应,并通过均匀半空间模型验证了计算的正确性;然后,对比关断期间段和关断后段的电磁响应,研究了下降沿时间对于异常探测的影响;最后,开展了两组电磁探测实验,结果表明关断期间段的电磁响应能够更有效地揭示浅层目标体,航空瞬变电磁系统对于浅层目标探测是一种有效的技术手段。
Airborne electromagnetic transient method enjoys the advantages of high-efficiency and the high resolution of electromagnetic anomalies, especially suitable for mining detection around goaf areas and deep exploration of minerals. In this paper, we calculated the full-wave airborne transient electromagnetic data, according to the result of numerical research, the advantage of switch-off time response in electromagnetic detection was proofed via experiments.Firstly, based on the full-wave airborne transient electromagnetic system developed by Jilin University(JLU-ATEM~Ⅰ),we proposed a method to compute the full-waveform electromagnetic(EM) data of 3D model using the FDTD approach and convolution algorithm, and verify the calculation by the response of homogenous half-space. Then, through comparison of switch-off-time response and off-time response, we studied the effect of ramp time on anomaly detection.Finally, we arranged two experimental electromagnetic detection, the results indicated that the switch-off-time response can reveal the shallow target more effectively, and the full-waveform airborne electromagnetic system is an effective technique for shallow target detection.
Airborne electromagnetic transient method enjoys the advantages of high-efficiency and the high resolution of electromagnetic anomalies, especially suitable for mining detection around goaf areas and deep exploration of minerals. In this paper, we calculated the full-wave airborne transient electromagnetic data, according to the result of numerical research, the advantage of switch-off time response in electromagnetic detection was proofed via experiments.Firstly, based on the full-wave airborne transient electromagnetic system developed by Jilin University(JLU-ATEM~Ⅰ),we proposed a method to compute the full-waveform electromagnetic(EM) data of 3D model using the FDTD approach and convolution algorithm, and verify the calculation by the response of homogenous half-space. Then, through comparison of switch-off-time response and off-time response, we studied the effect of ramp time on anomaly detection.Finally, we arranged two experimental electromagnetic detection, the results indicated that the switch-off-time response can reveal the shallow target more effectively, and the full-waveform airborne electromagnetic system is an effective technique for shallow target detection.
引文
[1] FOUNTAIN D. Airborne electromagnetic systems-50 years of development[J]. Exploration Geophysics, 1998,29:1-11.
[2] SMITH R S. Airborne electromagnetic methods:Applications to minerals, water and hydrocarbon exploration[J]. CSEG Recorder, 2010, 35(3):7-10.
[3] QIANG J K, LUO Y Z, TANG J T. The algorithm of all-time apparent resistivity for airborne transient electromagnetic(ATEM)survey[J]. Progress in Geophysics, 2010, 25:1657-1661.
[4] SATTEL D. A brief discussion of helicopter time-domain electromagnetic systems[C]//SEG International Meeting.New Orleans:SEG,2006:1268-1272.
[5] FOUNTAIN D. 60 years of airborne EM-focus on the last decade[C]//AEM2008-5th International Conference on Airborne Electromagnetics. Finland:AEM, 2008:1-5.
[6] ALLARD M. On the origin of HTEM species[C]//Proceedings of Exploration 07:5th Decennial International Conference on Mineral Exploration, Toronto, 2007:9-12.
[7] KILLEEN P G Exploration trends and developments in 2013[R]. Toronto, CAN:The Northern Miner, 2014.
[8] XU Y C, LIN J, LI S Y, ZHANG X S, WANG Y, JI Y J.Calculation of full-waveform airborne electromagnetic response with three-dimension finite-difference solution in time-domain[J]. Chinese Journal of Geophysics, 2012, 55:2105-2114. DOI:10.6038/j.issn.0001-5733.2012.06.032.(in Chinese)
[9] JI Y J, LUAN H, LI S Y, WAN L, WANG Y, XU Y C, LI L,LIN JUN. Resolution of full-waveform airborne TEM[J].Journal of Jilin University(Earth Science Edition), 2011, 41:885-891.(in Chinese)
[10] YIN C C, SMITH R S, HODGES G, ANNAN P. Modeling results of on-and off-time B and dB/dt for time-domain airborne EM systems[C]//70th EAGE Conference&Exhibition. Rome, 2008:1-4.
[11] YIN C C, HUANG W, LUAN F. The full-time electromagnetic modeling for time-domain airborne electromagnetic systems[J]. Chinese Journal of Geophysics,2013, 56:3153-3162. DOI:10.6038/cjg20130928.(in Chinese)
[12] QI Y Z, HUANG L, WANG X C, FANG G Y, YU G Airborne transient electromagnetic modeling and inversion under full attitude change[J]. IEEE Geoscience And Remote Sensing Letters, 2017, 99:1-5.
[13] JI Y J, ZHAO X J, GU J Y, LI D S, GUAN S S. Reduction of electromagnetic reflections in 3D airborne transient electromagnetic modeling:Application of the CFS-PML in source-free media[J]. International Journal of Antennas and Propagation, 2018:1846427.
[14] LIU G, ASTEN M W. Conductance-depth imaging of airborne TEM data[J]. Exploration Geophysics, 1993, 24:655-662.
[15] CLAPROOD M, CHOUTEAU M, CHENG L Z. Rapid detection and classification of airborne time-domain electromagnetic anomalies using weighted multi-linearregression[J]. Exploration Geophysics, 2008, 9:164-180.
[16] WANG T, HOHMANN G M. A finite-difference, timedomain solution for three-dimensional electromagnetic modeling[J]. Geophysics, 1993, 58:797-809.
[17] SUN H F, LI X, LI S C, QI Z P, WANG W P, SU M X, XUE Y G, LIU B. Three-dimensional FDTD modeling of TEM excited by a loop source considering ramp time[J]. Chinese Journal of Geophysics, 2013, 56:1049-1064.(in Chinese)
[18] YU M M. Research on full-wave recognition method of 3D anomalies based on ATEM.[D]. Changchun:Jilin University,2016.(in Chinese)
[19] JI Y J, LIN J, YU S B, WANG Z, WANG J. A study on solution of transient electromagnetic response during transmitting current turn-off in ATTEM system[J]. Chinese Journal of Geophysics, 2006,49:1884-1890.(in Chinese)
[20] ZHDANOV M S. Geophysical electromagnetic theory and methods[M]. Amsterdam:Elsevier, 2009.
[21] LI S Y, LIN J, YANG G H, TIAN P P, WANG Y, YU S B, JI Y J. Ground-Airborne electromagnetic signals de-noising uising a combined wavelet transform algorithm[J]. Chinese Journal of Geophysics, 2013, 56:3145-3152. DOI:10.6038/cig20130927.(in Chinese)
[22] JI Y J, LI D S, YUAN G Y, LIN J, DU S Y, XIE L J, WANG Y. Noise reduction of time domain electromagnetic data.Application of a combined wavelet denoising method[J].Radio Science, 2016, 51:680-689. DOI:10.1002/2016RS005985.
[23] LI D S, WANG Y, LIN J, YU S B, JI Y J. Electromagnetic noise reduction in grounded electrical source airborne transient electromagnetic signal using a stationary waveletbased denoising algorithm[J]. Near Surface Geophysics,2017, 15(2):163-173. DOI:10. 3997/1873-0604.2017003.
[2] SMITH R S. Airborne electromagnetic methods:Applications to minerals, water and hydrocarbon exploration[J]. CSEG Recorder, 2010, 35(3):7-10.
[3] QIANG J K, LUO Y Z, TANG J T. The algorithm of all-time apparent resistivity for airborne transient electromagnetic(ATEM)survey[J]. Progress in Geophysics, 2010, 25:1657-1661.
[4] SATTEL D. A brief discussion of helicopter time-domain electromagnetic systems[C]//SEG International Meeting.New Orleans:SEG,2006:1268-1272.
[5] FOUNTAIN D. 60 years of airborne EM-focus on the last decade[C]//AEM2008-5th International Conference on Airborne Electromagnetics. Finland:AEM, 2008:1-5.
[6] ALLARD M. On the origin of HTEM species[C]//Proceedings of Exploration 07:5th Decennial International Conference on Mineral Exploration, Toronto, 2007:9-12.
[7] KILLEEN P G Exploration trends and developments in 2013[R]. Toronto, CAN:The Northern Miner, 2014.
[8] XU Y C, LIN J, LI S Y, ZHANG X S, WANG Y, JI Y J.Calculation of full-waveform airborne electromagnetic response with three-dimension finite-difference solution in time-domain[J]. Chinese Journal of Geophysics, 2012, 55:2105-2114. DOI:10.6038/j.issn.0001-5733.2012.06.032.(in Chinese)
[9] JI Y J, LUAN H, LI S Y, WAN L, WANG Y, XU Y C, LI L,LIN JUN. Resolution of full-waveform airborne TEM[J].Journal of Jilin University(Earth Science Edition), 2011, 41:885-891.(in Chinese)
[10] YIN C C, SMITH R S, HODGES G, ANNAN P. Modeling results of on-and off-time B and dB/dt for time-domain airborne EM systems[C]//70th EAGE Conference&Exhibition. Rome, 2008:1-4.
[11] YIN C C, HUANG W, LUAN F. The full-time electromagnetic modeling for time-domain airborne electromagnetic systems[J]. Chinese Journal of Geophysics,2013, 56:3153-3162. DOI:10.6038/cjg20130928.(in Chinese)
[12] QI Y Z, HUANG L, WANG X C, FANG G Y, YU G Airborne transient electromagnetic modeling and inversion under full attitude change[J]. IEEE Geoscience And Remote Sensing Letters, 2017, 99:1-5.
[13] JI Y J, ZHAO X J, GU J Y, LI D S, GUAN S S. Reduction of electromagnetic reflections in 3D airborne transient electromagnetic modeling:Application of the CFS-PML in source-free media[J]. International Journal of Antennas and Propagation, 2018:1846427.
[14] LIU G, ASTEN M W. Conductance-depth imaging of airborne TEM data[J]. Exploration Geophysics, 1993, 24:655-662.
[15] CLAPROOD M, CHOUTEAU M, CHENG L Z. Rapid detection and classification of airborne time-domain electromagnetic anomalies using weighted multi-linearregression[J]. Exploration Geophysics, 2008, 9:164-180.
[16] WANG T, HOHMANN G M. A finite-difference, timedomain solution for three-dimensional electromagnetic modeling[J]. Geophysics, 1993, 58:797-809.
[17] SUN H F, LI X, LI S C, QI Z P, WANG W P, SU M X, XUE Y G, LIU B. Three-dimensional FDTD modeling of TEM excited by a loop source considering ramp time[J]. Chinese Journal of Geophysics, 2013, 56:1049-1064.(in Chinese)
[18] YU M M. Research on full-wave recognition method of 3D anomalies based on ATEM.[D]. Changchun:Jilin University,2016.(in Chinese)
[19] JI Y J, LIN J, YU S B, WANG Z, WANG J. A study on solution of transient electromagnetic response during transmitting current turn-off in ATTEM system[J]. Chinese Journal of Geophysics, 2006,49:1884-1890.(in Chinese)
[20] ZHDANOV M S. Geophysical electromagnetic theory and methods[M]. Amsterdam:Elsevier, 2009.
[21] LI S Y, LIN J, YANG G H, TIAN P P, WANG Y, YU S B, JI Y J. Ground-Airborne electromagnetic signals de-noising uising a combined wavelet transform algorithm[J]. Chinese Journal of Geophysics, 2013, 56:3145-3152. DOI:10.6038/cig20130927.(in Chinese)
[22] JI Y J, LI D S, YUAN G Y, LIN J, DU S Y, XIE L J, WANG Y. Noise reduction of time domain electromagnetic data.Application of a combined wavelet denoising method[J].Radio Science, 2016, 51:680-689. DOI:10.1002/2016RS005985.
[23] LI D S, WANG Y, LIN J, YU S B, JI Y J. Electromagnetic noise reduction in grounded electrical source airborne transient electromagnetic signal using a stationary waveletbased denoising algorithm[J]. Near Surface Geophysics,2017, 15(2):163-173. DOI:10. 3997/1873-0604.2017003.