空间假频对频率—波数域瑞利面波频散曲线反演的影响
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摘要
在地震勘探中,可以利用现有大炮地震记录中的瑞利面波频散信息提取频散曲线,进而反演近地表的速度结构,建立高密度的表层结构剖面。准确地提取瑞利面波频散曲线是提高近地表结构反演精度的前提。但由于地震勘探中大炮地震记录的道间距过大,利用频率—波数变换法提取频散曲线时,空间假频难以避免,这必然影响频散曲线提取和反演的效果。本文通过分析理论模型空间假频对频散曲线提取的影响,发现大道间距引起的空间假频会导致提取的频散曲线缺失高频信息,并通过频散曲线敏感度的理论分析,发现频散曲线高频部分对浅层横波速度更敏感。利用等厚分层阻尼最小二乘联合反演,分别对理论模型和实际数据进行了不同道间距的横波速度反演,反演结果表明空间假频引起的频散曲线高频段缺失会增大反演的整体相对误差,降低浅层反演精度和反演的稳定性,进而影响反演效果。
Near surface velocity structure and high-density structure profiles can be built by inverting the dispersion curve extracted from the Rayleigh-wave in seismic shot gathers.The accurate extraction of Rayleigh-wave dispersion curve can ensure the accuracy near surface structure inversion.However,spatial aliasing will affect dispersion curve extraction and the inversion of dispersion curve because of large receiver intervals in seismic shot gathers.Using a theoretical model,we find that the spatial aliasing causes high frequency information lack on the dispersion curve by large receiver intervals.We also find that high frequency dispersion curve is more sensitive to shear wave velocity of shallow layers.The joint inversion with the isopath layered and damped least squares is applied on both synthetic model and real data with different receiver intervals.Both of the tests demonstrate that the high frequency lack on dispersion curve increases the relative error of inversion,and harms the inversion stability due to the spatial aliasing.
Near surface velocity structure and high-density structure profiles can be built by inverting the dispersion curve extracted from the Rayleigh-wave in seismic shot gathers.The accurate extraction of Rayleigh-wave dispersion curve can ensure the accuracy near surface structure inversion.However,spatial aliasing will affect dispersion curve extraction and the inversion of dispersion curve because of large receiver intervals in seismic shot gathers.Using a theoretical model,we find that the spatial aliasing causes high frequency information lack on the dispersion curve by large receiver intervals.We also find that high frequency dispersion curve is more sensitive to shear wave velocity of shallow layers.The joint inversion with the isopath layered and damped least squares is applied on both synthetic model and real data with different receiver intervals.Both of the tests demonstrate that the high frequency lack on dispersion curve increases the relative error of inversion,and harms the inversion stability due to the spatial aliasing.
引文
[1]彭文.利用石油勘探面波信息调查表层结构的方法研究[博士论文].四川成都:成都理工大学,2007
[2]邹贤华等.准噶尔盆地南缘山地地震勘探采集方法与技术.天然气工业,2005,25(2):49～52Zou Xianhua et al.Acquisition methods and tech-niques of mountain seismic exploration in the south-ern fringe of Zhunge'er basin.Natural Gas Industry,2005,25(2):49～52
[3]Rayleigh L.On waves propagated along the planesurface of an elastic soil.Proc Lon Math Soc,1885,17(3):4～11
[4]杨成林等.瑞利波勘探.北京:地质出版社,1993
[5]裴江云,吴永刚,刘英杰.近地表低速带反演.长春地质学院学报,1997,24(3):317～320Pei Jiangyun,Wu Yonggang and Liu Yingjie.Nearsurface low velocity zone inversion.Journal ofChangchun University of Earth Sciences,1997,24(3):317～320
[6]周熙襄,王振国.利用瑞利面波调查表层结构的可行性探讨.石油地球物理勘探,2004,39(2):181～186Zhou Xixiang and Wang Zhenguo.Discussion on fea-sibility of using Rayleigh wave to investigate near-surface structure.OGP,2004,39(2):181～186
[7]王振国,周熙襄.再论利用瑞利面波调查表层结构的可行性.石油地球物理勘探,2004,39(5):505～508Wang Zhenguo and Zhou Xixiang.Discussion again a-bout possibility of using Rayleigh wave for investiga-tion of near-surface structure.OGP,2004,39(5):505～508
[8]彭文,周熙襄.利用瑞利面波调查表层结构的可行性分析.天然气工业,2006,26(9):54～57Peng Wen and Zhou Xixiang.Feasibility analysis ofsurveying surface structure with Rayleigh ground rollwave.Natural Gas Industry,2006,26(9):54～57
[9]李晶.面波在地震波场中的特性研究及其应用[博士论文].四川成都:成都理工大学,2006
[10]李桂元.f-k域滤波假频的消除方法.石油地球物理勘探,1994,29(增刊):86～92Li Guiyuan.Eliminating space aliasing in f-k do-main.OGP,1994,29(S):86～92
[11]宋先海,李端有等.瑞利波勘探理论及其应用.北京:中国水利水电出版社,2010
[12]渥.伊尔马兹著;刘怀山等译.地震资料分析:地震资料处理、反演和解释.北京:石油工业出版社,2006
[13]Xu Y,Xia J and Miller R D.Numerical investigationof implementation of air-earth boundary by acoustic-e-lastic boundary approach.Geophysics,2007,72(5):SM147～SM153
[14]凡友华,刘家琦.层状介质中瑞利面波的频散研究.哈尔滨工业大学学报,2001,33(5):577～581Fan Youhua and Liu Jiaqi.Research on the dispersionof Rayleigh waves in multilayered media.Journal ofHarbin Institute of Technology,2001,33(5):577～581
[15]王延坤,刘江平等.对缺失频段的瑞利波频散曲线反演的误差分析.工程地球物理学报,2006,3(1):38～44Wang Yankun and Liu Jiangping et al.The inversionof Rayleigh wave dispersion curve which lost frequen-cy range.Chinese Journal of Engineering Geophys-ics,2006,3(1):38～44
[16]Nazarian S,Stokoe K H and Hudson W R.Use ofspectral analysis of surface waves method for deter-mination of moduli and thickness of pavement sys-tems.Transportation Research Record 954,Trans-portation Research Board,Washington D C,1983
[17]Luo Yinhe et al.Joint inversion of high-frequencysurface waves with fundamental and higher modes.Journal of Applied Geophysics,2007,62(4):375～384
[2]邹贤华等.准噶尔盆地南缘山地地震勘探采集方法与技术.天然气工业,2005,25(2):49～52Zou Xianhua et al.Acquisition methods and tech-niques of mountain seismic exploration in the south-ern fringe of Zhunge'er basin.Natural Gas Industry,2005,25(2):49～52
[3]Rayleigh L.On waves propagated along the planesurface of an elastic soil.Proc Lon Math Soc,1885,17(3):4～11
[4]杨成林等.瑞利波勘探.北京:地质出版社,1993
[5]裴江云,吴永刚,刘英杰.近地表低速带反演.长春地质学院学报,1997,24(3):317～320Pei Jiangyun,Wu Yonggang and Liu Yingjie.Nearsurface low velocity zone inversion.Journal ofChangchun University of Earth Sciences,1997,24(3):317～320
[6]周熙襄,王振国.利用瑞利面波调查表层结构的可行性探讨.石油地球物理勘探,2004,39(2):181～186Zhou Xixiang and Wang Zhenguo.Discussion on fea-sibility of using Rayleigh wave to investigate near-surface structure.OGP,2004,39(2):181～186
[7]王振国,周熙襄.再论利用瑞利面波调查表层结构的可行性.石油地球物理勘探,2004,39(5):505～508Wang Zhenguo and Zhou Xixiang.Discussion again a-bout possibility of using Rayleigh wave for investiga-tion of near-surface structure.OGP,2004,39(5):505～508
[8]彭文,周熙襄.利用瑞利面波调查表层结构的可行性分析.天然气工业,2006,26(9):54～57Peng Wen and Zhou Xixiang.Feasibility analysis ofsurveying surface structure with Rayleigh ground rollwave.Natural Gas Industry,2006,26(9):54～57
[9]李晶.面波在地震波场中的特性研究及其应用[博士论文].四川成都:成都理工大学,2006
[10]李桂元.f-k域滤波假频的消除方法.石油地球物理勘探,1994,29(增刊):86～92Li Guiyuan.Eliminating space aliasing in f-k do-main.OGP,1994,29(S):86～92
[11]宋先海,李端有等.瑞利波勘探理论及其应用.北京:中国水利水电出版社,2010
[12]渥.伊尔马兹著;刘怀山等译.地震资料分析:地震资料处理、反演和解释.北京:石油工业出版社,2006
[13]Xu Y,Xia J and Miller R D.Numerical investigationof implementation of air-earth boundary by acoustic-e-lastic boundary approach.Geophysics,2007,72(5):SM147～SM153
[14]凡友华,刘家琦.层状介质中瑞利面波的频散研究.哈尔滨工业大学学报,2001,33(5):577～581Fan Youhua and Liu Jiaqi.Research on the dispersionof Rayleigh waves in multilayered media.Journal ofHarbin Institute of Technology,2001,33(5):577～581
[15]王延坤,刘江平等.对缺失频段的瑞利波频散曲线反演的误差分析.工程地球物理学报,2006,3(1):38～44Wang Yankun and Liu Jiangping et al.The inversionof Rayleigh wave dispersion curve which lost frequen-cy range.Chinese Journal of Engineering Geophys-ics,2006,3(1):38～44
[16]Nazarian S,Stokoe K H and Hudson W R.Use ofspectral analysis of surface waves method for deter-mination of moduli and thickness of pavement sys-tems.Transportation Research Record 954,Trans-portation Research Board,Washington D C,1983
[17]Luo Yinhe et al.Joint inversion of high-frequencysurface waves with fundamental and higher modes.Journal of Applied Geophysics,2007,62(4):375～384
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