均匀半空间有限长接地导线源地面电场响应特征
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摘要
本文分析了导线对可控源音频大地电磁勘探中电场的影响。在分析过程中,将有限长直接地导线源在层状介质中激发的电场的x分量分解为接地电极贡献的传到部分和通电长导线形成的感应部分,分别计算出在均匀半空间条件下,两部分及总电场随频率和收发距的变化规律。通过对计算结果的分析可见:在小收发距时,电场实部在低频区完全由接地电极部分贡献,在高频区由通电导线部分决定;电场虚部在低频区完全由通电导线部分决定,在高频区由接地电极部分和通电导线部分共同决定,且数值近似相等。在大收发距时,电场实部在低频区完全是由接地电极部分贡献,在高频区由接地电极部分和通电导线部分共同决定,且数值近似相等;电场虚部在低频区由通电导线贡献,在高频区由接地电极部分和通电导线部分共同决定,且数值近似相等。从上述分析可以看出,作为大收发距电磁法代表的可控源音频大地电磁法,其观测数据是由接地两端的传导分量和通电导线感应分量组成,并且感应分量贡献与传导贡献相当。由于导线敷设的非直线形,而引发与直导线理论不一致的结果。因此在数据采集工作中,必须考虑导线形状。同时要注意选择合适的收发距和工作频率,尽量把通电导线的影响降到最低。
This paper presents an analysis on the affect of ground-wire on the electric field in CSAMT exploration. The x component of the electric field generated by finite-long-straight ground wire in a stratified medium is decomposed into electrode part and wire part. In homogeneous half-space,we calculate changes of these two parts and the total electric field with frequency and receive-transmitter distance. Results show that when the receive-transmitter distance is small,the real part of the electric field is completely contributed by the electrode at low frequency and decided by wire at high frequency; while the imaginary part of the electric field is completely controlled by wire at low frequency and co-determined by wire and electrode at high frequency with largely same values. When the receiver-transmitter distance is large,the real part of the electric field is absolutely contributed by electrode at low frequency,and determined jointly by wire and electrode at high frequency with approximately equal values; while the imaginary part is contributed by wire at low frequency and co-contributed by electrode and wire at high frequency with approximately equal values. According these results,CSAMT as representative of the great receiver-transmitter distance electromagnetic methods,data by CSAMT consist of two parts: the conduction( electrode part) and induction( wire part) components,and both have largely the same contributions. However,as the wire is non-straight line when it is laid on the surface,the real results may be different from the straight line theory. Therefore,in the actual work,the line-current shape must be considered. At the same time,we should select proper receive-transmitter distances to lower the effect of the wire shape as much as possible.
This paper presents an analysis on the affect of ground-wire on the electric field in CSAMT exploration. The x component of the electric field generated by finite-long-straight ground wire in a stratified medium is decomposed into electrode part and wire part. In homogeneous half-space,we calculate changes of these two parts and the total electric field with frequency and receive-transmitter distance. Results show that when the receive-transmitter distance is small,the real part of the electric field is completely contributed by the electrode at low frequency and decided by wire at high frequency; while the imaginary part of the electric field is completely controlled by wire at low frequency and co-determined by wire and electrode at high frequency with largely same values. When the receiver-transmitter distance is large,the real part of the electric field is absolutely contributed by electrode at low frequency,and determined jointly by wire and electrode at high frequency with approximately equal values; while the imaginary part is contributed by wire at low frequency and co-contributed by electrode and wire at high frequency with approximately equal values. According these results,CSAMT as representative of the great receiver-transmitter distance electromagnetic methods,data by CSAMT consist of two parts: the conduction( electrode part) and induction( wire part) components,and both have largely the same contributions. However,as the wire is non-straight line when it is laid on the surface,the real results may be different from the straight line theory. Therefore,in the actual work,the line-current shape must be considered. At the same time,we should select proper receive-transmitter distances to lower the effect of the wire shape as much as possible.
引文
Andreis D,Mac Gregor L.2007.Controlled-source electromagnetic sounding in shallow water:Principles and applications[J].Geophysics,73(1):F21-F32.
Chave A D,Cox C S.1982.Controlled electromagnetic sources for measuring electrical conductivity beneath the oceans:1.Forward problem and model study[J].Journal of Geophysical Research:Solid Earth,87(B7):5327-5338.
Chave A D.1983.Numerical integration of related Hankel transforms by quadrature and continued fraction expansion[J].Geophysics,48(12):1671-1686.
Christensen N B,Fitzpatrick A,Munday T.2010.Fast approximate 1Dinversion of frequency domain electromagnetic data[J].Near Surface Geophysics,8(1):1-15.
Constable S,Cox C S.1996.Marine controlled-source electromagnetic sounding:2.The PEGASUS experiment[J].Journal of Geophysical Research:Solid Earth,101(B3):5519-5530.
Constable S,Srnka L J.2007.An introduction to marine controlledsource electromagnetic methods for hydrocarbon exploration[J].Geophysics,72(2):WA3-WA12.
Guptasarma D,Singh B.1997.New digital linear filters for Hankel J0and J1transforms[J].Geophysical Prospecting,45(5):745-762.
Hu X Y,Peng R H,Wu G J,Wang W P,Huo G P,Han B.2013.Mineral exploration using CSAMT data:Application to Longmen region metallogenic belt,Guangdong Province,China[J].Geophysics,78(3):B111-B119.
Kaufman A A,Keller G V.1983.Frequency and transient soundings[M].Amsterdam:Elsevier.21-25.
Liu Guoxing.2005.The principle and method of electrical prospecting[M].Beijing:Geological Publishing House:125-133(in Chinese).
Liu Yunhe.2011.Research on 3-D controlled source electromagnetic method inversion using nonlinear conjugate gradients[D].Changchun:Jilin University:50-55(in Chinese).
Li Jinghe,He Zhanxiang,Xiong Bin.2018.Fast 2D forward modeling and inversion of CSEM with topography in the frequency domain[J].Geology and Exploration,54(2):325-331(in Chinese with English abstract).
Nabighian M N.1987.Electromagnetic method in applied geophysics:Volume 1:Theory[M].Society of Exploration Geophysicists,71-83.
Nekut A G,Spies B R.1989.Petroleum exploration using controlledsource electromagnetic methods[J].Proceedings of the IEEE,77(2):338-362.
Piao Huarong.1990.Principle of electromagnetic sounding method[M].Beijing:Geological Publishing House:241-252(in Chinese).
Plessix R E,Mulder W A.2008.Resistivity imaging with controlledsource electromagnetic data:Depth and data weighting[J].Inverse Problems,24(3):034012.
Roux E,García X.2014.Optimizing an experimental design for a CSEMexperiment:Methodology and synthetic tests[J].Geophysical Journal International,197(1):135-148.
Schamper C,Rejiba F,Guérin R.2012.1D single-site and laterally constrained inversion of multifrequency and multicomponent groundbased electromagnetic induction data-Application to the investigation of a near-surface clayey overburden[J].Geophysics,77(4):WB19-WB35.
Streich R.2016.Controlled-source electromagnetic approaches for hydrocarbon exploration and monitoring on land[J].Surveys in Geophysics,37(1):47-80.
Streich R,Becken M.2011.Electromagnetic fields generated by finitelength wire source:Comparison with point dipole solutions[J].Geophysical Prospecting,59:361-374.
Sun Hongyan,Li Ruchuan,Wang Shumin,Liu Tianliang.2004.Effects of the cagniard resistivity errors by the antenna azimuth errors in the CSAMT measurements[J].Geology and Exploration,(4):80-81(in Chinese).
Thiesson J,Kessouri P,Schamper C,Tabbagh A.2014.Calibration of frequency-domain electromagnetic devices used in near-surface surveying[J].Near Surface Geophyscis,12(4):481-491.
Um E S,Alumbaugh D L.2007.On the physics of the marine controlledsource electromagnetic method[J].Geophysics,72(2):WA13-WA26.
Wang Jun,Wang Qingyi.1992.A fast method for calculating the frequency-domain EM response of a finitely long grounded wire over a layered earth[J].Geology and Prospecting,28(3):30-38(in Chinese).
Weng A H,Liu Y H,Yin C C,et al.2016.Singularity-free Green’s function for EM sources embedded in a stratified medium[J].Applied Geophysics,13(1):25-36.
Wu Xiaoping,Wu Yunpeng.2012.A comparative analysis for the dipole source and the long line source electromagnetic response[J].Progress in Geophysics,27(6):2602-2608(in Chinese with English abstract).
Xu Zhifeng,Hu Wenbao.2013.Electromagnetic field excited by long line sources in frequency domain on layered earth model[J].Journal of Jilin University(Earth Science Edition),43(1):275-281(in Chinese with English abstract).
Yin Changchun.1994.One-dimensional modeling of CSAMT method and evaluation of calculation precision[J].Journal of Changchun U-niversity of Earth Sciences,24(4):438-453(in Chinese).
Zhao Guomao,Li Zhihua,Zhu Xudong,Feng Yanqian.2010.Research on CSAMT 1-D modeling of long wire source[J].Journal of Railway Engineering Society,8:21-24(in Chinese).
Zonge K L,Hughes L J.1991.Controlled source audio-frequency magnetotellurics[M]//Electromagnetic Methods in Applied Geophysics:Volume 2,Application,Parts A and B.Society of Exploration Geophysicists:713-810.
刘国兴.2005.电法勘探原理与方法[M].北京:地质出版社:125-133.
刘云鹤.2011.三维可控源音频大地电磁法非线性共轭梯度反演研究[D].长春:吉林大学:50-55.
李静和,何展翔,熊彬.2018.起伏地形频率域可控源电磁二维快速正反演[J].地质与勘探,54(2):325-331.
朴化荣.1990.电磁测深发原理[M].北京:地质出版社:241-252.
孙鸿雁,李汝传,王书民,林天亮.2004.可控源音频大地电磁测深中水平磁场探头方向偏差对卡尼亚视电阻率的影响[J].地质与勘探,(4):80-81.
王军,王庆乙.1992.层状大地有限长接地导线频域电磁响应的快速计算方法[J].地质与勘探,28(3):30-38.
吴小平,吴云鹏.2012.非零长线源与偶极源的电磁响应比较分析[J].地球物理学进展,27(6):2602-2608.
许志峰,胡文宝.2013.层状大地频率域长导线源激发的电磁场[J].吉林大学学报(地球科学版),43(1):275-281.
殷长春.1994.可控源音频大地电流法一维正演及精度评价[J].长春地质学院学报,24(4):438-453.
赵广茂,李志华,朱旭东,冯彦谦.2010.长导线源CSAMT一维正演研究[J].铁道工程学报,8:21-24.
Chave A D,Cox C S.1982.Controlled electromagnetic sources for measuring electrical conductivity beneath the oceans:1.Forward problem and model study[J].Journal of Geophysical Research:Solid Earth,87(B7):5327-5338.
Chave A D.1983.Numerical integration of related Hankel transforms by quadrature and continued fraction expansion[J].Geophysics,48(12):1671-1686.
Christensen N B,Fitzpatrick A,Munday T.2010.Fast approximate 1Dinversion of frequency domain electromagnetic data[J].Near Surface Geophysics,8(1):1-15.
Constable S,Cox C S.1996.Marine controlled-source electromagnetic sounding:2.The PEGASUS experiment[J].Journal of Geophysical Research:Solid Earth,101(B3):5519-5530.
Constable S,Srnka L J.2007.An introduction to marine controlledsource electromagnetic methods for hydrocarbon exploration[J].Geophysics,72(2):WA3-WA12.
Guptasarma D,Singh B.1997.New digital linear filters for Hankel J0and J1transforms[J].Geophysical Prospecting,45(5):745-762.
Hu X Y,Peng R H,Wu G J,Wang W P,Huo G P,Han B.2013.Mineral exploration using CSAMT data:Application to Longmen region metallogenic belt,Guangdong Province,China[J].Geophysics,78(3):B111-B119.
Kaufman A A,Keller G V.1983.Frequency and transient soundings[M].Amsterdam:Elsevier.21-25.
Liu Guoxing.2005.The principle and method of electrical prospecting[M].Beijing:Geological Publishing House:125-133(in Chinese).
Liu Yunhe.2011.Research on 3-D controlled source electromagnetic method inversion using nonlinear conjugate gradients[D].Changchun:Jilin University:50-55(in Chinese).
Li Jinghe,He Zhanxiang,Xiong Bin.2018.Fast 2D forward modeling and inversion of CSEM with topography in the frequency domain[J].Geology and Exploration,54(2):325-331(in Chinese with English abstract).
Nabighian M N.1987.Electromagnetic method in applied geophysics:Volume 1:Theory[M].Society of Exploration Geophysicists,71-83.
Nekut A G,Spies B R.1989.Petroleum exploration using controlledsource electromagnetic methods[J].Proceedings of the IEEE,77(2):338-362.
Piao Huarong.1990.Principle of electromagnetic sounding method[M].Beijing:Geological Publishing House:241-252(in Chinese).
Plessix R E,Mulder W A.2008.Resistivity imaging with controlledsource electromagnetic data:Depth and data weighting[J].Inverse Problems,24(3):034012.
Roux E,García X.2014.Optimizing an experimental design for a CSEMexperiment:Methodology and synthetic tests[J].Geophysical Journal International,197(1):135-148.
Schamper C,Rejiba F,Guérin R.2012.1D single-site and laterally constrained inversion of multifrequency and multicomponent groundbased electromagnetic induction data-Application to the investigation of a near-surface clayey overburden[J].Geophysics,77(4):WB19-WB35.
Streich R.2016.Controlled-source electromagnetic approaches for hydrocarbon exploration and monitoring on land[J].Surveys in Geophysics,37(1):47-80.
Streich R,Becken M.2011.Electromagnetic fields generated by finitelength wire source:Comparison with point dipole solutions[J].Geophysical Prospecting,59:361-374.
Sun Hongyan,Li Ruchuan,Wang Shumin,Liu Tianliang.2004.Effects of the cagniard resistivity errors by the antenna azimuth errors in the CSAMT measurements[J].Geology and Exploration,(4):80-81(in Chinese).
Thiesson J,Kessouri P,Schamper C,Tabbagh A.2014.Calibration of frequency-domain electromagnetic devices used in near-surface surveying[J].Near Surface Geophyscis,12(4):481-491.
Um E S,Alumbaugh D L.2007.On the physics of the marine controlledsource electromagnetic method[J].Geophysics,72(2):WA13-WA26.
Wang Jun,Wang Qingyi.1992.A fast method for calculating the frequency-domain EM response of a finitely long grounded wire over a layered earth[J].Geology and Prospecting,28(3):30-38(in Chinese).
Weng A H,Liu Y H,Yin C C,et al.2016.Singularity-free Green’s function for EM sources embedded in a stratified medium[J].Applied Geophysics,13(1):25-36.
Wu Xiaoping,Wu Yunpeng.2012.A comparative analysis for the dipole source and the long line source electromagnetic response[J].Progress in Geophysics,27(6):2602-2608(in Chinese with English abstract).
Xu Zhifeng,Hu Wenbao.2013.Electromagnetic field excited by long line sources in frequency domain on layered earth model[J].Journal of Jilin University(Earth Science Edition),43(1):275-281(in Chinese with English abstract).
Yin Changchun.1994.One-dimensional modeling of CSAMT method and evaluation of calculation precision[J].Journal of Changchun U-niversity of Earth Sciences,24(4):438-453(in Chinese).
Zhao Guomao,Li Zhihua,Zhu Xudong,Feng Yanqian.2010.Research on CSAMT 1-D modeling of long wire source[J].Journal of Railway Engineering Society,8:21-24(in Chinese).
Zonge K L,Hughes L J.1991.Controlled source audio-frequency magnetotellurics[M]//Electromagnetic Methods in Applied Geophysics:Volume 2,Application,Parts A and B.Society of Exploration Geophysicists:713-810.
刘国兴.2005.电法勘探原理与方法[M].北京:地质出版社:125-133.
刘云鹤.2011.三维可控源音频大地电磁法非线性共轭梯度反演研究[D].长春:吉林大学:50-55.
李静和,何展翔,熊彬.2018.起伏地形频率域可控源电磁二维快速正反演[J].地质与勘探,54(2):325-331.
朴化荣.1990.电磁测深发原理[M].北京:地质出版社:241-252.
孙鸿雁,李汝传,王书民,林天亮.2004.可控源音频大地电磁测深中水平磁场探头方向偏差对卡尼亚视电阻率的影响[J].地质与勘探,(4):80-81.
王军,王庆乙.1992.层状大地有限长接地导线频域电磁响应的快速计算方法[J].地质与勘探,28(3):30-38.
吴小平,吴云鹏.2012.非零长线源与偶极源的电磁响应比较分析[J].地球物理学进展,27(6):2602-2608.
许志峰,胡文宝.2013.层状大地频率域长导线源激发的电磁场[J].吉林大学学报(地球科学版),43(1):275-281.
殷长春.1994.可控源音频大地电流法一维正演及精度评价[J].长春地质学院学报,24(4):438-453.
赵广茂,李志华,朱旭东,冯彦谦.2010.长导线源CSAMT一维正演研究[J].铁道工程学报,8:21-24.