联合应用τ-p变换法和相移法提取面波频散曲线
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摘要
在常见的多阶模式频散曲线提取方法中,f-k法要求空间域和时间域的采样都是等间隔的,如果记录中含有坏道,就会对f-k谱产生很大影响,从而影响频散曲线的提取精度。τ-p变换法对基阶模式低频段的提取效果较差,而对高阶模式的分辨能力较高。相移法对基阶模式提取效果好,但对高阶模式的分辨率不高。本文提出了一种改进的频散曲线提取方法,即联合应用τ-p变换法和相移法提取频散曲线,该法的基本思想是先对地震记录分别用τ-p变换法和相移法得到两种f-VR剖面,将两种f-VR剖面用各自的最大值归一化后再相加,将叠加结果作为最终的f-VR剖面。理论模型合成记录与实际资料处理结果均表明,本文提出的频散曲线提取方法兼顾了τ-p变换法和相移法的优点,既补充了基阶模式低频段的信息,又保证了高阶模式得到有效分辨,取得了理想的提取效果。
For the common multiple mode dispersion curve extraction methods,f-k method requires equal sampling rate in both space domain and time domain,if there are bad traces in the datasets,the f-k spectrum could be greatly affected,so the extraction accuracy of the dispersion curve could be affected as well.The τ-p transform method has a bad extraction effect for low frequency band of the fundamental mode,but it has very good resolving ability for high order mode.Phase shift method is just the opposite with better extraction effect for fundamental mode and lower resolution for high order mode.An improved dispersion curve extraction method was proposed in this paper,the basic idea of the method is just joint application of the τ-p transform method and phase shift method,as a result the advantage of each method could be combined,the extraction effect for low frequency band of the fundamental mode was enhanced while the resolution for high order mode got raised.The theoretical model synthetic record and field data processing results show that the new joint method proposed in this paper combined the advantage of both τ-p transform method and phase shift method,so that the ideal extraction effect was achieved.
For the common multiple mode dispersion curve extraction methods,f-k method requires equal sampling rate in both space domain and time domain,if there are bad traces in the datasets,the f-k spectrum could be greatly affected,so the extraction accuracy of the dispersion curve could be affected as well.The τ-p transform method has a bad extraction effect for low frequency band of the fundamental mode,but it has very good resolving ability for high order mode.Phase shift method is just the opposite with better extraction effect for fundamental mode and lower resolution for high order mode.An improved dispersion curve extraction method was proposed in this paper,the basic idea of the method is just joint application of the τ-p transform method and phase shift method,as a result the advantage of each method could be combined,the extraction effect for low frequency band of the fundamental mode was enhanced while the resolution for high order mode got raised.The theoretical model synthetic record and field data processing results show that the new joint method proposed in this paper combined the advantage of both τ-p transform method and phase shift method,so that the ideal extraction effect was achieved.
引文
[1]李庆春,邵广周,刘金兰等.瑞利面波勘探的过去、现在和未来.地球科学与环境学报,2006,28(3):74～77
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[3]Jianghai Xia,Richard D Mand Choon B Park.Ad-vantages of calculating shear-wave velocity fromsur-face waves with higher modes.SEG Technical Pro-gram Expanded Abstracts,2000,19:312～315
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[5]陈淑珍,刘怀林.基于τ-p变换的频散曲线及其算法实现.武汉大学学报,2000,46(1):123～126
[6]Park C B,Miller R D,Xia J.Imaging dispersion curves of surface waves on multi-channel record.SEG Technical Program Expanded Abstracts,1998,17:1377～1380
[7]Kristen B.Determination of near-surface variabili-ty using Rayleigh waves[D].University of Alberta,2000
[8]邵广周,李庆春,梁志强.液体表层层状介质导波频散曲线研究.地球物理学报,2007,50(2):915～920
[9]Li Qingchun,Cheng Jianwei,Wu Peng et al.High res-olution radon transform and wavefield separation.Proceedings of the2nd International Conference on Environment and Engineering Geophysics,2006,190～195
[10]Shao Guangzhou,Li Qingchun,Li Jianguo.Surface wave extracting from reflection seismic data and structure imaging of shallowseafloor.Proceedings of the3rd International Conference on Environment and Engineering Geophysics,2008,186～190
[2]Xia J,Miller R D,Park C B and Tian G.Inversion of high frequency surface waves with fundamental and higher modes.Journal of Applied Geophysics,2003,52(1):45～57
[3]Jianghai Xia,Richard D Mand Choon B Park.Ad-vantages of calculating shear-wave velocity fromsur-face waves with higher modes.SEG Technical Pro-gram Expanded Abstracts,2000,19:312～315
[4]Park C B,Miller R D,Xia J.Higher mode observa-tion by the MASW method.SEG Technical Program Expanded Abstracts,1999,18:524～527
[5]陈淑珍,刘怀林.基于τ-p变换的频散曲线及其算法实现.武汉大学学报,2000,46(1):123～126
[6]Park C B,Miller R D,Xia J.Imaging dispersion curves of surface waves on multi-channel record.SEG Technical Program Expanded Abstracts,1998,17:1377～1380
[7]Kristen B.Determination of near-surface variabili-ty using Rayleigh waves[D].University of Alberta,2000
[8]邵广周,李庆春,梁志强.液体表层层状介质导波频散曲线研究.地球物理学报,2007,50(2):915～920
[9]Li Qingchun,Cheng Jianwei,Wu Peng et al.High res-olution radon transform and wavefield separation.Proceedings of the2nd International Conference on Environment and Engineering Geophysics,2006,190～195
[10]Shao Guangzhou,Li Qingchun,Li Jianguo.Surface wave extracting from reflection seismic data and structure imaging of shallowseafloor.Proceedings of the3rd International Conference on Environment and Engineering Geophysics,2008,186～190
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