摘要
大地电磁测深(MT)曲线畸变是一个普遍存在的现象。如果在采用常规旋转主轴求取TE和TM方式的电阻率和相位前,不对畸变的阻抗数据进行畸变消除,将会获得不正确的电阻率和相位,影响后续的数据处理解释成果。
本文从一般情况出发推导出地质噪声对阻抗的畸变公式。通过对理论模型受畸变因子影响的正演计算,得出了一些有规律性的结论,对研究畸变因子对阻抗的影响有指导意义。
本文采用简单明了的求取消除畸变后的区域阻抗方法,经理论和实测数据的反演计算,被证实是有效的。该方法避免了GB分解方法的一些问题:1.求解参数多。2.需要对求解参数作限制。3.观测误差影响反演结果。4.在有些情况下,不易求解。5.损失三维电性信息。
本文根据测区电阻率分布特征,通过选择所需电阻率、相位曲线,采用遗传算法求取畸变因子的方法实用有效。
Curve distortion is common in MT survey. If the distortion of the impedance data is not eliminated, the resistivity and phase of the TE and TM mode calculated by the common rotating principal axis may be wrong, which effluence on the result of data processing and interpretation.The paper deduces the impedance distortion formula resulting from geological noise from general situation. By forwardly calculating the theoretical models under the effluence of the distortion factors, the author draws some regular conclusions, which are conductive to study the impedance effluence from the distortion factors.In this paper, a method to calculate regional impedance from the data in which the distortions have been eliminated is presented. It proves to be effective by inverse calculation of the theoretic data and the observed data in the field. The method avoids the following problems of GB decomposition. Firstly, there are too many parameters to be calculated. Secondly, it is necessary to constraint the parameters to be calculated, thirdly, the observed errors have much effluence on the inverse results, fourthly, it is difficult to calculate in some cases, and the last is that the 3-D information is lost.The necessary resistivity and phase curves are selected according to the features of resistivity and phase in the field and the GA is used to calculate the distortion factors, which proves to be practical and effective.
引文
[1] 陈乐寿、王光锷 大地电磁测深[M] 地质出版社 1990年
[2] 刘国栋、陈乐寿 大地电磁测深研究[M] 地震出版社 1994年
[3] 王家映 石油电法勘探[M] 石油工业出版社 1992年
[4] 朴化荣 电磁测深法原理[M] 地质出版社 1990年
[5] A.A.考夫曼,G.V凯勒,王建谋译频率域和时间域电磁测深[M] 地质出版社1987年
[6] 王家映 我国大地电磁测深研究新进展[J]地球物理学报 Vol.40增1997
[7] 王家映关于大地电磁的静校正问题[J]地质科技情报 Vol.11,No.1 1992
[8] 刘国栋、赵国泽 大地电磁法新进展[J]地球科学进展 Vol.9,No.4 1994
[9] 翁爱华、刘国兴西方大地电磁测深理论发展现状[J]世界地质 Vol.17,No.1 1998
[10] 王永涛、白改先 大地电磁测深曲线的畸变及校正[J]石油物探 Vol.36,No.1 1997
[11] 魏胜等 全MT张量分解技术及其应用[J]应用地球物理学进展 1996
[12] 晋光文、江钊、孙洁 区域三维大地电磁阻抗张量畸变效应的Mohr圆分析[J]地震地喷 Vol.18,No.4 1996
[13] 高洪伟,张胜业阻抗张量分解进行大地电磁静校正的研究[J]地质科技情报 Vol.17 No.1 1998
[14] 晋光文、孙洁、王继军 地形对大地电磁测深资料的影响[J]地震地质 Vol.19.No.4 1997
[15] 苏鸿尧、何展翔表层电性不均匀对大地电磁测深曲线的畸变研究[J]地质科技情报 Vol.9,No.4 2000
[16] 龙大全 介绍大地电磁法曲线的超相位现象[J]石油物探译丛[J] No.1 1991
[17] 杨生、鲍光淑等 MT法中静态效应及阻抗张量静态校正法[J] 中南工业大学学报 vol.33,No.1,2002
[18] 尹兵祥 王光锷 大地电磁阻抗正则分解的地质含义[J]地球物理学报 Vol.44,No.2,2001
[19] 石琳珂 孙铭心等 地球物理遗传反演方法[M]地震出版社 2000
[20] 陈国良等 遗传算法及其应用[M]人民邮电出版社 1996
[21] 徐丽娜 神经网络控制 哈尔滨工业大学出版社[M] 1999
[22] 侯俊胜、管志宁 遗传算法在磁异常反演中的应用物探与化探[J] Vol.20,No.3 1996
[23] 潘美芹、贺国平等 基于改进遗传算法的多维函数的优化计算[J]山东科技大学学报(自然科学版)[J] Vol.19,No.2 2000
[24] 张荣峰 采用生物遗传算法的大地电磁测深资料反演[J]物探化探计算技术[J] Vol.18.No.1 1996
[25] 张小路 重磁反演的群体优生遗传算法[J]地质与勘探 Vol.35,No.5 1999
[26] 孙洁、晋光文等 大地电磁测深的噪声干扰[J]物探与化探 Vol.24,No.2 2000
[27] 何继善 电法勘探的发展和展望[J]地球物理学报 Vol.40(增) 1997
[28] 刘国栋 我国大地电磁测深的发展[J]地球物理学报 Vol.37(增) 1994
[29] 王建谋、陈乐寿等译 大地电磁测深译文集(第一集[M]
[30] 牛之琏等 脉冲瞬变电磁法[M]中南工业大学出版 1986
[31] 戴世坤 复杂地形和地表条件MT资料处理和二维反演成像及其应用 内部资料 1997
[32] 何继善等 可控源音频大地电磁法[M]中南工业大学出版 1990
[33] 何继善 电磁列阵剖面法及其进展[J]物探化探译丛 No.4、5 1992
[34] 汤井田等 复杂地球物理信号的分离研究报告[M]中南工业大学出版 1995
[35] 罗延钟等 可控源音频大地电磁法理论和应用研究
[36] 魏胜等 ROBUST估计在大地电磁资料处理中的应用[J]中国地球物理学会年刊 1993
[37] 宋守根等 小波分析与电磁测深中静态效应的识别、分离及压制[M]中国地球物理学会年刊 1993
[38] 王家映 电磁阵列剖面法的基本原理[J]地球科学 15(增) 1990
[39] 江钊等 ROBUST估计及其在大地电磁资料处理中的初步应用[M]《电磁方法研究与勘探》地震出版社 1993
[40] 王家映 大地电磁拟地震解释法[M]石油工业出版社 1995
[41] 晋光文等 一种大地电磁张量阻抗计算方法[J]地球物理学报 25(增) 1982
[42] 何玉辉 天然电磁场测深[J]物探化探计算技术 Vol.21,No.2 1997
[43] 严良俊等 南方碳酸盐岩地区电磁勘探方法买验及效果[M]江汉石油学院 1998
[44] 胡玉平等 江苏下扬子地区MT面积普查施工总结 华北有色物探公司 2001
[45] 晋光文 大地电磁资料的反演问题[J]地球科学 15(增) 1990
[46] 孙必俊等 关于大地电磁资料的反演问题[J]地球物理学报 Vol.28 1985
[47] Groom,R.w.& Baily, R.C.,Decomposition of magnetotelluric impedance tensor ir the presence of local three-dimensional galvanic distortion, J. Geophys.Res.,94,1989.
[48] Groom,R.w.& Baily, R.C.,Analytical investigations of the effects of the near-surface three-dimensional galvanic scatterers on MT tensor decompositions,Geophysics.56,1991.
[49] Groom,R.w., Kurtz, R.D,& Jones,A.G.et al.,A quantitantive methodology to extract regional magnetotelluric impedances and determine the dimension of the conductivity structure,Geophys.J.Int., 113,1993.
[50] Chave,A.D.&smith,J.T.,On electric and magnetic galvanic distortion tensor decomposition,J.Geophys.Res.,99,1994.
[51] Jones,A.G.& Groom,KW.,Strike-angle determination from the magnetotelluric impedance tensor in the presence of noise and local distortion:rotate at your peril! Geophys.J.Int, 113,1993
[52] Smith,J.T.& Booker, J.R.,Rapid inversion of two-and three-dimensional rnagnetotelluric cata,J.Geophys.Res.,96,1991.
[53] Bahr, k. Interpretation of the magnetotelluric impedance tensor:regional induction and local telluric distortion.J Geophys. 66,1988
[54] Bahr, k. Geological noise in magnetotelluric data: a classification of distortion type. Physics of the Earth and Planetary Interiors,66,1991
[55] Lilley F.E.M. Magnetotelluric analysis using Molnr circles. Geophysics,58(10) 1993
[56] Wnanarnaker, P.E.,Hohmann,G.W.& Ward, S.H.,Magnetotelluric responses of three-dimensional bodies in layered earths,Geophysics,49,1984.
[57] Zhang,P.,Roberts,R .G.& Peelersen, L.B.,Magnettotelluric strike rules,Geophysics,52,1987.
[58] Zhang,P.,Pedersen & Mureschal,M.et al.,Channeling contribution to tipper vectors:A magnetic equivalent to electrical distortion,Geophys. J Int., 113,1993.
[59] Sutarno,d.,Vozoff, k., Robust M-estimation of magnetotelluric impedance tensors Expl.Geophys.22 1989
[61] Vozoff.k, Magnetotelluric method Geophysics Reprint Series 4157 1986
[62] Cagniard.l., Basic the magnetotelluric method of geophysical prospecting Geophysies,18,1953
[63] Tikhonov, A.N., Determination of the electrical charactericstics of the deep strata of the Earth'crust Doki,akad.nank.SSr t3 1950
[64] Sims,w.e.Bostick, F.X.Jr, and Smith, H.W, The estimatation of magnetotelluric Impedance (?)nsor elements from measured data, Geophysics Vol 36,1971
[65] Write,R.E.,Estimation of signal spectra and related quantities by means od the multiple (?)oherency function Geophys. Prosp. Vol.21 1973
[66] Kao,D.W. and Rankin.d. Enhancement of signal-to-noise ratio in (?)gnetotellturic (?)ata, Geophysics,Vol.42,1977
[67] Gouban,w.m.,Gamble,T.D.and Clerke,.j;Magnetotelluric data analysis:removal of bias,Geophysic Vol 43,1978
[68] Iliceto,V.and Santarato,G.;A new attempt at automatic data processing in magnetotelluric,Geoexplorafion,Vol. 17,1979
[69] Gamble T.D;Gaubau,w.m and Clerke,J. Magnetotelluric with a remote magnctic reference Geophyics,vol.44,No. 1 1979
[70] Kaufman A.A;Reduction of the geological noise in magnetotelluric sounding Geoexplaoration Vol.25 1988