弱各向异性介质地震波传播特征分析
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摘要
随着油气田勘探精度要求越来越高,各向异性已成为不得不考虑的重要因素,因此对地震波在各向异性介质中传播特征的研究具有一定的价值。利用Thomsen提出的弱各向异性理论,通过理论模型数值计算,分析了Thomsen各向异性参数对弱各向异性VTI介质中三种体波的影响。分析结果表明:①参数ε、δ分别影响qP波大角度、中小角度传播的各向异性;②参数(ε-δ)影响qSV波中等角度传播时的各向异性;③参数γ影响qSH波大角度传播的各向异性,且群速度的各向异性要比相速度的各向异性更明显,并会出现复杂的交会区。通过这些研究分析,进一步认识了弱各向异性介质相速度及群速度随各向异性参数变化的规律。
With the increasing needs of exploration precision, seismic anisotropy has to be taken as a critical issue. Thus the research of seismic wave propagation characteristic of the anisotropic media has a certain value. Based on the theory of the weak anisotropy proposed by Thomsen, this paper analysis the effects of Thomsen anisotropic parameters on three body waves of weak anisotropic VTI media by numerical calculating the theoretical model. The results show that the anisotropic characters of qP-wave at larger、intermediate and small angle depend on ε、δ respectively, the anisotropic characters of qSV-wave at intermediate angle depend on (ε-δ), the anisotropic characters of qSH-wave at large angle depend on γ,and the anisotropic characters of group velocity which may represent cusps is more obvious than phase velocity. Through these research and analysis, we further understand the law of phase velocity and group velocity according to the anisotropy parameters in the weak anisotropic media.
With the increasing needs of exploration precision, seismic anisotropy has to be taken as a critical issue. Thus the research of seismic wave propagation characteristic of the anisotropic media has a certain value. Based on the theory of the weak anisotropy proposed by Thomsen, this paper analysis the effects of Thomsen anisotropic parameters on three body waves of weak anisotropic VTI media by numerical calculating the theoretical model. The results show that the anisotropic characters of qP-wave at larger、intermediate and small angle depend on ε、δ respectively, the anisotropic characters of qSV-wave at intermediate angle depend on (ε-δ), the anisotropic characters of qSH-wave at large angle depend on γ,and the anisotropic characters of group velocity which may represent cusps is more obvious than phase velocity. Through these research and analysis, we further understand the law of phase velocity and group velocity according to the anisotropy parameters in the weak anisotropic media.
引文
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[3]CARCIONE J M,KOSLOFF D,KOSLOFF R.Wavepropagation simulation in a linear viscoacoustic medium[J].Geophys J R.astr Soc,1988,95(3):597.
[4]郭智奇,刘财,杨宝俊,等.粘弹各向异性介质中地震波场模拟与特征[J].地球物理学进展,2007,22(3):800.
[5]郭智奇.粘弹各向异性介质波场模拟与储层信息研究[D].长春:吉林大学,2008.
[6]赵峰帆,韩立国,林炎,等.TTI介质相速度理论研究[J].吉林大学学报(地球科学版),2006,36(专辑):121.
[7]韩颜颜,郭智奇,刘财,等.弹性各向异性介质速度特征分析[J].吉林大学学报(地球科学版),2008,38(增刊):80.
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[10]BERRYMAN J G.Long-Wave elastic anisotropy pro-duced by horizontal layering[J].Geophys Res.,1979,67(11):4427.
[2]WHITE J E.Computed waveforms in transversely iso-tropic media[J].Geophysics,1982,47(5):64.
[3]CARCIONE J M,KOSLOFF D,KOSLOFF R.Wavepropagation simulation in a linear viscoacoustic medium[J].Geophys J R.astr Soc,1988,95(3):597.
[4]郭智奇,刘财,杨宝俊,等.粘弹各向异性介质中地震波场模拟与特征[J].地球物理学进展,2007,22(3):800.
[5]郭智奇.粘弹各向异性介质波场模拟与储层信息研究[D].长春:吉林大学,2008.
[6]赵峰帆,韩立国,林炎,等.TTI介质相速度理论研究[J].吉林大学学报(地球科学版),2006,36(专辑):121.
[7]韩颜颜,郭智奇,刘财,等.弹性各向异性介质速度特征分析[J].吉林大学学报(地球科学版),2008,38(增刊):80.
[8]THOMSEN L.Weak elastic anisotropy[J].Geophysics,1986,51(10):1954.
[9]TSVANKIN I.seismic signatures and analysis of reflec-tion data in anisotropic media[M].Pergamon,2001.
[10]BERRYMAN J G.Long-Wave elastic anisotropy pro-duced by horizontal layering[J].Geophys Res.,1979,67(11):4427.
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