YUAN Shao-ye, LIN Jun, SONG Shuang, SUN De-li, TENG Fei
（College of Instrumentation & Electrical Engineering, Jilin University, Jilin 130061, China）
Abstract： Transient electromagnetic method (TEM), as a non-seismic geophysical exploration mainstream electromagnetic method, is widely used in oil, gas, mineral and other underground resources exploration areas. The coil sensor is generally used to collect data. In view of the problems of incomplete information of the abnormal body and the data loss in the existing TEM single-component coil sensor, a three-component TEM coil sensor is designed. By analyzing the relationship between sensor sensitivity and coil structure parameters, the coil structure and turns are designed. By analyzing the frequency response characteristics of the TEM magnetic field sensor, the signal distortion is reduced by using the under-damped matching mode. By analyzing the distribution of various noise sources of the magnetic sensor, the appropriate amplifier is selected to reduce the background noise. Finally, a three-component TEM induction magnetic field sensor is designed. The weight of the sensor is controlled at 3.2 kg and the working frequency is 10 mHz-10 kHz. The background noises of X and Y components probably keep in 1.5×10-8 V/〖KF(〗Hz〖KF)〗 and sensitivities are 8.4 and 9.8 nT/s, respectively, the background noise of vertical component is 2.1×10-7 V/〖KF(〗Hz〖KF)〗 and sensitivity is 18.5 nT/s. Compared with the existing single-component TEM receiving magnetic field sensor, the designed sensor realizes the signal acquisition of three components. Without too much increase in volume and total weight, it improves the sensitivity of the sensor and reduces the background noise, thus the signal-to-noise ratio (SNR) of the signal is improved.
Key words： transient electromagnetic method (TEM); three-component air-core coil sensor; under-damped matching; noise analysis
CLD number： TP212.1 Document code： A
Article ID： 1674-8042（2019）01-0028-010 doi： 10.3969/j.issn.1674-8042.2019.01.005
References
［1］ Lv G Y. Current status and development trend of transient EM method. Computing Techniques for Geophysical & Geochemical Exploration, 2007, 29(S1): 111-115 .
［2］ Ji Y J, Wang Y, Xu J, et al. Development and application of the grounded long wire source airborne electromagnetic exploration system based on an unmanned airship. Chinese Journal of Geophysics, 2013, 56(11): 3640-3650.
［3］ Wu S Y. Research on key technologies of data acquisition in semi-aviation electro-magnetic exploration system. Chengdu: Chengdu University of Technology, 2014.
［4］ Li X, Zhang Y Y. Development history and new development of ground-to-air transient electromagnetic system. In: Proceedings of 2014 China Earth Science Joint Academic Annual Meeting on Topic 24: Shallow Surface Geophysics, Beijing, 2014: 19-21.
［5］ Zhu K G, Lin J, Liu C S, et al. One-dimensional forward modeling and depth of detection in frequency domain aeronautical electromagnetic method. Journal of Geophysics, 2008, 23(6): 1943-1946.
［6］ Mogi T, Tanaka Y, Kusunoki K, et al. Development of grounded electrical source airborne transient EM (GREATEM). Exploration Geophysics, 1998, 29(2): 61-64.
［7］ Ito H, Mogi T, Jomori A, et al. Further investigations of underground resistivity structures in coastal areas using grounded-source airborne electromagnetics. Earth, Planets and Space, 2011, 63(8): e9-e12.
［8］ Liu J. Study on three-component transient electromagnetic response law of conductive thin plate. Changsha: Central South University, 2009.
［9］ Scrivens S. A comparison between helicopter and fixed-wing time-domain electromagnetic systems. Ottawa: Carleton University, 2005.
［10］ Zonge K L, Carlson N. The utility of horizontal component measurements in random-walk TEM surveys. 2002［2018-09-27］. http:∥www.zonge.com/wp-content/uploads/2013/06/ENV_TEM_HorizontalComponentsSAGEEP2003.pdf.
［11］ Xi Z Z, Liu J, Long X, et al. Three-component measurement in transient electromagnetic method. Journal of Central South University, 2010, 41(1): 272-276.
［12］ Tan S C, Wang H, Xi Z Z, et al. Three-component joint processing and interpretation of transient electromagnetic method. Chinese Journal of Nonferrous Metals, 2012, 22(3): 909-914.
［13］ Liu G D. Transient electromagnetic instrument-taking PROTEM as an example. In: Proceedings of China International Earth Electromagnetics Symposium, 2007.
［14］ Seran H C, Fergeau P. An optimized low-frequency three-axis search coil magnetometer for space research. Review of Scientific Instruments, 2005, 76(4): 44502.
［15］ Hua Z W, Yun D Q, Song L L, et al. Development of search coil magnetometer based on magnetic flux negative feedback structure. Chinese Journal of Geophysics, 2013, 56(11): 3683-3689.
［16］ Niu Z L. Principle of transient electromagnetic method. Changsha: Central South University Press, 2007.
［17］ Tumanski S. Induction coil sensors—a review. Measurement Sci & Tech, 2007, 18(3): R31-R46.
［18］ Paperno E, Grosz A. A miniature and ultralow power search coil optimized for a 20 mHz to 2 kHz frequency range. Journal of Applied Physics, 2009, 105(7): 2147483647.
［19］ He Z R. Noise analysis and design of operational amplifier circuit. Microelectronics, 2006, 36(2): 148-153.
［20］ Yuan Z, Li H. Practical design of low noise op amp preamplifier. Instrument Technology, 2000, (6)： 20-22.
［21］ Qian B. Time domain analysis and parameter selection of receiving coils of M1 avionics system. Journal of Jilin University, 1982, (2)： 129-144.
［22］ Wang H J. Influence characteristics of damping coefficient on transient electro-magnetic observation signals. Chinese Journal of Geophysics, 2010, 53(2)： 428-434.
［23］ Zhang S, Liu Z X, Chen S D. Research on damping characteristics of transient electromagnetic sensor. Chinese Journal of Geophysics, 2014, 57(2)： 662-670.
地空瞬变电磁三分量空芯线圈传感器设计
元绍烨， 林 君， 宋 爽， 孙德立， 滕 飞
（吉林大学 仪器科学与电气工程学院， 吉林 长春 130061）
摘 要： 瞬变电磁法（TEM）作为地球物理非地震探勘的主要电磁方法之一， 广泛应用于油气、 矿产等地下资源探测， 采集数据时一般使用线圈传感器。 针对现有的TEM单分量线圈传感器存在的反应异常体信息不全面和数据易丢失的问题， 本文设计了一个三分量TEM线圈传感器。 通过分析传感器灵敏度与线圈结构参数的关系， 对线圈结构、 匝数等进行了设计； 通过分析TEM磁场传感器频率响应特点， 采用欠阻尼匹配模式减小信号失真； 通过分析磁传感器各类噪声源分布， 选定了适宜的放大器， 降低了本底噪声。 所研制的三分量TEM 感应式磁场传感器重量控制在3.2 kg， 工作频段为10 mHz-10 kHz， X分量和Y分量的本底噪声保持在1.5×10-8 V/〖KF(〗Hz〖KF)〗， 灵敏度分别为8.4 nT/s和9.8 nT/s， 垂直分量的本底噪声达到2.1×10-7 V/〖KF(〗Hz〖KF)〗， 灵敏度为18.5 nT/s。 与现有的单分量TEM接收磁场传感器相比， 本设计实现了三个分量的信号采集， 且在体积和总重量增大不多的基础上， 降低了传感器的灵敏度和本底噪声， 提高了信号的信噪比。
关键词： 瞬变电磁法； 三分量线圈传感器； 欠阻尼匹配； 噪声分析
引用格式： YUAN Shao-ye, LIN Jun, SONG Shuang, et al. Design of ground-airborne TEM three-component air-core coil sensor. Journal of Measurement Science and Instrumentation, 2019, 10(1)： 28-37. ［doi： 10.3969／j.issn.1674-8042.2019.01.005］
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