Abstract:The surface-hole transient electromagnetic method (SHTEM) is used to explore deep mineral resources by which field source is excited on surface and transient responses are observed through receiving coil in borehole. The mutual inductance coefficient and induced voltage between equivalent eddy current ring and Rx are calculated based on the principle of equivalent eddy current ring method. By establishing a mathematic model of multiple thin-plate conductors, the response superimposed field is calculated and simulated under the condition that there are combinations of multiple thin conductive plates underground to study the surface-hole transient electromagnetic anomaly responses of multiple conductors and analyze their characteristics and rules. It is considered that multiple combinations of thin plate orebodies can be distinguished through SHTEM when they are close to the borehole.
Jiang B Y. Practical near-field magnetic source transient electromagnetic exploration[M]. Beijing: Geological Publishing House, 1998: 199- 237. (in Chinese) 蒋邦远. 实用近区磁源瞬变电磁法勘探[M]. 北京: 地质出版社, 1998: 199-237.
[2]
Niu Z L. Principle of time domain electromagnetic method[M]. Changsha: Central South University Press, 2007: 249-267. (in Chinese) 牛之琏. 时间域电磁法原理[M]. 长沙: 中南大学出版社, 2007: 249-267.
[3]
Buselli G, Lee S K. Modelling of drill-hole TEM responses from multiple targets covered by a conductive overburden[J]. Exploration Geophysics, 1996, 27(2/3): 141-153.
[4]
Singh N P, Mogi T. Electromagnetic response of a large circular loop source on a layered earth: A new computation method[J]. Pure and Applied Geophysics, 2005, 162(1): 181-200.
[5]
Richards D J. CRAE's approach to downhole TEM at Broken Hill[J]. Exploration Geophysics, 1987, 18(3): 279-284.
[6]
Eaton P A, Hohmann G W. The influence of a conductive host on two-dimensional borehole transient electromagnetic responses[J]. Geophysics, 1984, 49(7): 861-869.
[7]
West R C, Ward S H. The borehole transient electromagnetic response of a three-dimensional fracture zone in a conductive half-space[J]. Geophysics, 1988, 53(11): 1469-1478.
[8]
Macnae J, Staltari G. Classification of sign changes in Borehole TEM decays[J]. Exploration Geophysics, 1987, 18(3): 331-339.
[9]
Dyck A V, West G F. The role of simple computer models in interpretations of wide-band, drill-hole electromagnetic surveys in mineral exploration[J]. Geophysics, 1984, 49(7): 957-980.
[10]
Telford W M, Geldart L P, Sheriff R E. Applied geophysics[M]. Cambridge: Cambridge University Press, 1990: 353.
[11]
Paul C R. Inductance: Loop and partial[M]. Hoboken: John Wiley and Sons Ltd, 2010: 196-206.
[12]
Dwight H B. Tables of integrals and other mathematical data[M]. 4th ed. New York: MacMillan, 1964: 45.
[13]
Jeffrey A. Handbook of mathematical formulas and integrals[M]. San Diego: Academic Press, 1995: 178.
[14]
Vella L. Taking downhole EM underground, at hill 50 decline, mount magnet, Western Australia[J]. Exploration Geophysics, 1997, 28(1/2): 141-146.
[15]
Zhang Z, Xiao J. Inversions of surface and borehole data from large- loop transient electromagnetic system over a 1-D earth[J]. Geophysics, 2001, 66(4): 1090-1096.
[16]
Aziz A A, Strack K, Hanstein T. Surface-to-borehole TEM for reservoir monitoring[C]//SEG Technical Program Expanded Abstracts 2011. Society of Exploration Geophysicists, 2011: 1882-1886.
[17]
Li J H, Liu S C, Jiao X F, et al. Three-dimensional forward modeling for surface-borehole transient electromagnetic method[J]. Oil Geophysical Prospecting, 2015, 50(3): 556-564. 李建慧, 刘树才, 焦险峰, 等. 地-井瞬变电磁法三维正演研究[J]. 石油地球物理勘探, 2015, 50(3): 556-564.
[18]
Yang H Y, Yue J H, Xu Z Y, et al. Transient electromagnetic method modeling in ground-borehole model with overburden influence[J]. Journal of Jilin University (Earth Science Edition), 2016, 46 (5): 1527-1537. 杨海燕, 岳建华, 徐正玉, 等. 覆盖层影响下典型地-井模型瞬变电磁法正演[J]. 吉林大学学报(地球科学版), 2016, 46(5): 1527-1537.
[19]
Paggi J, Macklin D. Discovery of the Eureka volcanogenic massive sulphide lens using downhole electromagnetics[J]. Exploration Geophysics, 2016, 47(3): 248-257.
[20]
Kolaj M, Smith R. Robust conductance estimates from spatial and temporal derivatives of borehole electromagnetic data[J]. Geophysics, 2014, 79(3): E115-E123.