与频率相关的各向异性横波分裂参数提取算法
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摘要
在地震频率范围内,含较大裂缝多孔岩石的各向异性参数表现出频率相关性。本文基于矢量褶积模型建立了分析多分量VSP数据的与频率相关各向异性的横波分裂参数提取算法。该算法可以在频域中针对单个频率提取横波各向异性参数(快横波的极化方向以及快、慢横波的时差),避免了传统算法中分段滤波可能带来的误差。通过对地震合成记录的数值分析,证明了该算法的可行性和正确性,并与传统算法结果进行了比较。结果显示,与频率相关的各向异性横波分裂参数可以从地震数据中提取。
Anisotropic parameters of the porous rocks with larger scale fractures are usually frequency-dependent in the seismic frequency range.Based on the vector convolutional model for shear-wave propagating through an anisotropic medium,developed by Zeng and MacBeth(1993),we develop a new algebraic technique for extracting shear-wave splitting parameters from VSP multi-component data in frequency-dependent anisotropic medium.By this new technique,anisotropic parameters,including polarization direction of the shear-waves and time-delay between fast and slow shear-waves,can be estimated for each frequency in the frequency domain.This avoids errors caused by band-passed filter in the conventional technique.The feasibility and validity of the technique is tested on synthetic seismograms and a comparison with the conventional technique is also given.The results demonstrate that the frequency-dependent anisotropy shear-wave splitting parameters can be extracted directly from seismic data by this technique.
Anisotropic parameters of the porous rocks with larger scale fractures are usually frequency-dependent in the seismic frequency range.Based on the vector convolutional model for shear-wave propagating through an anisotropic medium,developed by Zeng and MacBeth(1993),we develop a new algebraic technique for extracting shear-wave splitting parameters from VSP multi-component data in frequency-dependent anisotropic medium.By this new technique,anisotropic parameters,including polarization direction of the shear-waves and time-delay between fast and slow shear-waves,can be estimated for each frequency in the frequency domain.This avoids errors caused by band-passed filter in the conventional technique.The feasibility and validity of the technique is tested on synthetic seismograms and a comparison with the conventional technique is also given.The results demonstrate that the frequency-dependent anisotropy shear-wave splitting parameters can be extracted directly from seismic data by this technique.
引文
[1]Liu E et al.Velocity and attenuation anisotropy causedby microcracks and macrofractures in a multiazimuth-al reverse VSP.Canadian Journal of ExplorationGeophysics,1993,29(1):177~188
[2]Queen J H et al.Geophysical methods of fracture de-tection and estimation.The Leading Edge,1992,11(6):19~21
[3]Marson-Pidgeon K et al.Frequency-dependent ani-sotropy in Wellington,New Zealand.GeophysicalResearch Letters,1997,24(24):3297~3300
[4]Liu K et al.Frequency band-dependence of S-wavesplitting in China mainland and its implications.Sci-ence in China(Series D),2001,44(7):659~665
[5]Zeng X et al.Algebraic processing techniques for es-timating shear-wave splitting in near-offset VSP data:theory.Geophysical Prospecting,1993,41(8):1033~1066
[6]Zeng X et al.Shear-wave VSP data processing foranisotropy.Changsha(China):NUDT press,1997
[7]曾新吾等.各向异性介质中的矢量褶积模型与横波分裂算法.石油地球物理勘探,1998,33(2):191~197Zeng Xin-wu et al.Vector convolution model andshear-wave splitting algorithm in anisotropic media.OGP,1998,33(2):191~197
[8]Chapman M.Frequency-dependent anisotropy due tomeso-scale fractures in the presence of equant porosi-ty.Geophysical Prospecting,2003,51(5):369~379
[9]Sonja Maultzsch et al.Modeling frequency-dependentseismic anisotropy in fluid-saturated rock with alignedfractures:implication of fracture size estimation fromanisotropic measurements.Geophysical Prospecting,2003,51(5):381~392
[10]Sonja Maultzsch et al.The potential of measuringfracture sizes with frequency-dependent shear-wavesplitting.First Break,2003,21(7):43~49
[11]Thomsen L.Elastic anisotropy due to aligned cracksin porous rock.Geophysical Prospecting,1995,43(6):805~829
[2]Queen J H et al.Geophysical methods of fracture de-tection and estimation.The Leading Edge,1992,11(6):19~21
[3]Marson-Pidgeon K et al.Frequency-dependent ani-sotropy in Wellington,New Zealand.GeophysicalResearch Letters,1997,24(24):3297~3300
[4]Liu K et al.Frequency band-dependence of S-wavesplitting in China mainland and its implications.Sci-ence in China(Series D),2001,44(7):659~665
[5]Zeng X et al.Algebraic processing techniques for es-timating shear-wave splitting in near-offset VSP data:theory.Geophysical Prospecting,1993,41(8):1033~1066
[6]Zeng X et al.Shear-wave VSP data processing foranisotropy.Changsha(China):NUDT press,1997
[7]曾新吾等.各向异性介质中的矢量褶积模型与横波分裂算法.石油地球物理勘探,1998,33(2):191~197Zeng Xin-wu et al.Vector convolution model andshear-wave splitting algorithm in anisotropic media.OGP,1998,33(2):191~197
[8]Chapman M.Frequency-dependent anisotropy due tomeso-scale fractures in the presence of equant porosi-ty.Geophysical Prospecting,2003,51(5):369~379
[9]Sonja Maultzsch et al.Modeling frequency-dependentseismic anisotropy in fluid-saturated rock with alignedfractures:implication of fracture size estimation fromanisotropic measurements.Geophysical Prospecting,2003,51(5):381~392
[10]Sonja Maultzsch et al.The potential of measuringfracture sizes with frequency-dependent shear-wavesplitting.First Break,2003,21(7):43~49
[11]Thomsen L.Elastic anisotropy due to aligned cracksin porous rock.Geophysical Prospecting,1995,43(6):805~829
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