倾斜电各向异性介质大地电磁正演研究
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摘要
研究地层电各向异性性质能够圈定沉积地层中的油气储层和与地球动力学过程、地震预报有关的深部线性构造。通过得到的N层倾斜电各向异性介质大地电磁响应公式,在不同的电各向异性系数、地层倾角、倾斜层厚度参数下,对电各向异性倾斜地层模型进行了正演计算。结果表明:当电各向异性系数、地层倾角、地层厚度三者中任一变量改变时,视电阻率曲线的形态基本保持不变,但视电阻率曲线振幅值变化较大;视电阻率曲线对地层倾角参数的变化反应最为敏感;电各向异性系数的增加,能突显薄层电阻率异常。这有助于以后的电各向异性介质大地电磁反演和应用研究。
The study of the electric anisotropy properties of strata can delineate oil and gas reservoirs in the strata and the deep linear structure related to geodynamic process and earthquake prediction.On the basis of magnetotelluric response formula in N-layer tilted electric anisotropic media obtained by the authors and under the condition of different electric anisotropy coefficients,dip angles of strata and thicknesses of tilted beds,the authors conducted forward calculation of the model for electric anisotropic tilted strata.The results show that,when any one of the three variables(electrical anisotropy coefficient,dip angle of strata,and depth of strata) is changed,the shape of the apparent resistivity curve remains basically unchanged,but the amplitude value of the apparent resistivity curve varies considerably,that the apparent resistivity curve is most sensitive to the change of the dip angle parameter of strata,and that the increase of the electric anisotropy coefficient can clearly demonstrate the resistivity anomaly of the thin layer.The results achieved by the authors will be helpful to electric anisotropic media magnetotelluric inversion and applied research in future.
The study of the electric anisotropy properties of strata can delineate oil and gas reservoirs in the strata and the deep linear structure related to geodynamic process and earthquake prediction.On the basis of magnetotelluric response formula in N-layer tilted electric anisotropic media obtained by the authors and under the condition of different electric anisotropy coefficients,dip angles of strata and thicknesses of tilted beds,the authors conducted forward calculation of the model for electric anisotropic tilted strata.The results show that,when any one of the three variables(electrical anisotropy coefficient,dip angle of strata,and depth of strata) is changed,the shape of the apparent resistivity curve remains basically unchanged,but the amplitude value of the apparent resistivity curve varies considerably,that the apparent resistivity curve is most sensitive to the change of the dip angle parameter of strata,and that the increase of the electric anisotropy coefficient can clearly demonstrate the resistivity anomaly of the thin layer.The results achieved by the authors will be helpful to electric anisotropic media magnetotelluric inversion and applied research in future.
引文
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[14]Negi J G,Saraf P D.Impedance of a plane electromagnetic wave at the surface of a layered conducting earth with dipping anisotropy[J].Geophysical Prospecting,1972,20(4):785-799.
[15]Negi J G,Saraf P D.Inductive sounding of a stratified earth with transition layer resting on dipping anisotropic beds[J].Geophysical Prospecting,1973,21(4):635-647.
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[17]Negi J G,Saraf P D.Asthenospheric parameters of dipping plate regions by magnetotelluric investigations[J].Physics of the Earth and Planetary Interiors,1981,25(3):255-262.
[2]内吉J G,萨拉夫P D.大地介质电磁各向异性问题[M].邹永辉,陈德志,译.北京:地质出版社,1992.
[3]王家映.我国大地电磁测深研究新进展[J].地球物理学报,1997,40(1):206-216.
[4]霍光谱,胡祥云,刘敏.各向异性介质中大地电磁正演研究综述[J].地球物理学进展,2011,26(6):1976-1982.
[5]O'Brien D P,Morrison H F.Electromagnetic fields in an n-layer anisotropic half-space[J].Geophysics,1967,32(4):668-677.
[6]Reddy I K,Rankin D.Magnetotelluric Effect of Dipping ANISOTROPIES*[J].Geophysical Prospecting,1971,19(1):84-97.
[7]石应骏,刘国栋,吴广耀,等.大地电磁测深法[M].北京:地震出版社,1984.
[8]刘国栋,陈乐寿.大地电磁测深研究[M].北京:地震出版社,1984.
[9]林长佑,武玉霞,杨长福,等.水平层状对称各向异性介质的大地电磁资料反演[J].地球物理学报,1996,39:342-348.
[10]阮爱国,李清河.EDA各向异性层状介质MT正演模拟[J].华南地震,1999,19(4):8-13.
[11]陈冬,王彦春,汪中浩,等.水平井地层电阻率各向异性研究[J].物探与化探,2007,31(3):239-241.
[12]李金铭.地电场与电法勘探[M].北京:地质出版社,2005.
[13]陈杰.MATLAB宝典[M].北京:电子工业出版社,2007.
[14]Negi J G,Saraf P D.Impedance of a plane electromagnetic wave at the surface of a layered conducting earth with dipping anisotropy[J].Geophysical Prospecting,1972,20(4):785-799.
[15]Negi J G,Saraf P D.Inductive sounding of a stratified earth with transition layer resting on dipping anisotropic beds[J].Geophysical Prospecting,1973,21(4):635-647.
[16]Negi J G,Saraf P D.Possibility of deep crustal probing in orogenic regions by studying variations of the surface impedance parameter of natural electromagnetic fields[J].Radio Science,1976,11(10):787-793.
[17]Negi J G,Saraf P D.Asthenospheric parameters of dipping plate regions by magnetotelluric investigations[J].Physics of the Earth and Planetary Interiors,1981,25(3):255-262.
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