基于两步SVD变换的零偏VSP资料上下行波场分离方法
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摘要
垂直地震剖面(Vertical Seismic Profiling,VSP)资料处理中波场分离是关键问题之一.随着属性提取技术的发展,新的属性参数(例如Q值)提取技术对波场分离的保真性要求越来越高.本文改进了传统奇异值分解(Singular Value Decomposition,SVD)法,给出了一种对波场的动力学特征具有更好的保真性,可以作为Q值提取的预处理步骤的零偏VSP资料上下行波场分离方法.该方法通过两步奇异值分解变换实现:第一步,排齐下行波同相轴,利用SVD变换压制部分下行波能量;第二步,在剩余波场中排齐上行波同相轴,使用SVD变换提取上行波场.在该方法的实现过程中,压制部分下行波能量后的剩余波场中仍然存在较强的下行波干扰,使得上行波同相轴的排齐比较困难.本文给出了一种通过极大化多道数据线性相关程度(Maximize Coherence,MC)排齐同相轴的算法,在一定程度上解决了低信噪比下排齐同相轴的问题.将本文提出的方法用于合成数据和实际资料的处理,并与传统SVD法的处理结果进行对比,结果表明本文提出的波场分离方法具有良好的保真性,得到波场的质量明显优于传统SVD法.通过对本文方法和传统SVD法处理合成数据得到的下行波场提取Q值,然后进行对比可知,本文方法可以有效提高所提取Q值的准确性,适合作为Q值提取的预处理步骤.
With the development of seismic attribute analysis technique,the fidelity of waveform and amplitude becomes important to wavefield separation method.In this paper,we present a zero-offset vertical seismic profiling(VSP) wavefield separation method with good fidelity.The method is based on singular value decomposition(SVD) filtering and has four stages: first,aligning events of downgoing wave by static time shifting each trace of VSP;second,suppressing downgoing wave by high-pass SVD filtering;third,aligning events of upgoing wave by static time shifting each trace of downgoing wave suppressed wavefield;fourth,extracting upgoing wave by low-pass SVD filtering.It is difficult to calculate the time shift of each trace for aligning events of upgoing wave,as the residual downgoing wave in downgoing wave suppressed wavefield is not very weak.In this paper,we calculate the time shift via the largest singular value maximization algorithm.Using the synthetic and real data examples,we demonstrate that the results of our method have good fidelity,and are better than the results of traditional SVD method.The result of synthetic data also show that our method can be used as preprocess of Q estimation.
With the development of seismic attribute analysis technique,the fidelity of waveform and amplitude becomes important to wavefield separation method.In this paper,we present a zero-offset vertical seismic profiling(VSP) wavefield separation method with good fidelity.The method is based on singular value decomposition(SVD) filtering and has four stages: first,aligning events of downgoing wave by static time shifting each trace of VSP;second,suppressing downgoing wave by high-pass SVD filtering;third,aligning events of upgoing wave by static time shifting each trace of downgoing wave suppressed wavefield;fourth,extracting upgoing wave by low-pass SVD filtering.It is difficult to calculate the time shift of each trace for aligning events of upgoing wave,as the residual downgoing wave in downgoing wave suppressed wavefield is not very weak.In this paper,we calculate the time shift via the largest singular value maximization algorithm.Using the synthetic and real data examples,we demonstrate that the results of our method have good fidelity,and are better than the results of traditional SVD method.The result of synthetic data also show that our method can be used as preprocess of Q estimation.
引文
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[3]Simaan M.Optimum array filters for array data signalprocessing.IEEE Trans.of Acoustics Speech and SignalProcessing,1983,31(4):1006-1015.
[4]Simaan M,Love P L.Optimum suppression of coherentsignals with linear move out in seismic data.Geophysics,1984,49(3):215-226.
[5]王成礼.VSP多道迭代递归滤波波场分离及应用.石油地球物理勘探,1991,26(2):169-178.Wang C L.A method for VSP wave field separation usingmultitrace iterative recursion filtering,and its application.Oil Geophysical Prospecting(in Chinese),1991,26(2):169-178.
[6]Freire S L M,Ulrych T J.Application of singular valuedecomposition to vertical seismic profiling.Geophysics,1988,53(6):778-785.
[7]Rieber F.Visual presentation of elastic wave patterns undervarious structural conditions.Geophysics,1936,1(2):196-218.
[8]Carswell A,Tag R,Dillistone C,et al.A new method of wavefield separation in VSP data processing.54th Annual SEG Meeting,SEG Expanded Abstracts,1984:40-42.
[9]朱光明.垂直地震剖面方法.北京:石油工业出版社,1988.Zhu G M.Vertical Seismic Profiling(in Chinese).Beijing:Petroleum Industry Press,1988.
[10]Blias E.VSP wavefield separation:Wave-by-wave optimization approach.Geophysics,2007,72(4):47-55.
[11]杜婧,王尚旭,刘国昌等.基于局部斜率属性的VSP波场分离研究.地球物理学报,2009,52(7):1867-1872.Du J,Wang S X,Liu G C,et al.VSP wavefield separation using local slopes attribute.Chinese J.Geophys.(in Chinese),2009,52(7):1867-1872.
[12]Gao J H,Yang S L,Wang D X,et al.Estimation of quality factor Q from the instantaneous frequency at the envelope peak of a seismic signal.Journal of Computational Acoustics,2011,19(2):155-179.
[13]Hyvrinen A,Karhunen J,Oja E.Independent Component Analysis.New York:John Wiley&Sons,Inc.,2001.
[14]Montagne R,Vasconcelos G L.Optimized suppression of coherent noise from seismic data using the Karhunen-Loève transform.Physical Review E,2006,74(1):16213-1-16213-8.
[15]凌永祥,陈明逵.计算方法教程.西安:西安交通大学出版社,2005.Ling Y X,Chen M K.A Course in Computational Method(in Chinese).Xi′an:Xi′an Jiaotong University Press,2005.
[16]Ganley D C.A method for calculating synthetic seismograms which include the effects of absorption and dispersion.Geophysics,1981,46(8):1100-1107.
[17]高静怀,杨森林,王大兴.利用VSP资料直达波的包络峰值处瞬时频率提取介质品质因子.地球物理学报,2008,51(3):853-861.Gao J H,Yang S L,Wang D X.Quality factor extraction using instantaneous frequency at envelope peak of direct waves of VSP data.Chinese J.Geophys.(in Chinese),2008,51(3):853-861.
[2]Balch A H,Lee M W,Miller J J,et al.The use of verticalseismic profiles in seismic investigations of the earth.Geophysics,1982,47(6):906-918.
[3]Simaan M.Optimum array filters for array data signalprocessing.IEEE Trans.of Acoustics Speech and SignalProcessing,1983,31(4):1006-1015.
[4]Simaan M,Love P L.Optimum suppression of coherentsignals with linear move out in seismic data.Geophysics,1984,49(3):215-226.
[5]王成礼.VSP多道迭代递归滤波波场分离及应用.石油地球物理勘探,1991,26(2):169-178.Wang C L.A method for VSP wave field separation usingmultitrace iterative recursion filtering,and its application.Oil Geophysical Prospecting(in Chinese),1991,26(2):169-178.
[6]Freire S L M,Ulrych T J.Application of singular valuedecomposition to vertical seismic profiling.Geophysics,1988,53(6):778-785.
[7]Rieber F.Visual presentation of elastic wave patterns undervarious structural conditions.Geophysics,1936,1(2):196-218.
[8]Carswell A,Tag R,Dillistone C,et al.A new method of wavefield separation in VSP data processing.54th Annual SEG Meeting,SEG Expanded Abstracts,1984:40-42.
[9]朱光明.垂直地震剖面方法.北京:石油工业出版社,1988.Zhu G M.Vertical Seismic Profiling(in Chinese).Beijing:Petroleum Industry Press,1988.
[10]Blias E.VSP wavefield separation:Wave-by-wave optimization approach.Geophysics,2007,72(4):47-55.
[11]杜婧,王尚旭,刘国昌等.基于局部斜率属性的VSP波场分离研究.地球物理学报,2009,52(7):1867-1872.Du J,Wang S X,Liu G C,et al.VSP wavefield separation using local slopes attribute.Chinese J.Geophys.(in Chinese),2009,52(7):1867-1872.
[12]Gao J H,Yang S L,Wang D X,et al.Estimation of quality factor Q from the instantaneous frequency at the envelope peak of a seismic signal.Journal of Computational Acoustics,2011,19(2):155-179.
[13]Hyvrinen A,Karhunen J,Oja E.Independent Component Analysis.New York:John Wiley&Sons,Inc.,2001.
[14]Montagne R,Vasconcelos G L.Optimized suppression of coherent noise from seismic data using the Karhunen-Loève transform.Physical Review E,2006,74(1):16213-1-16213-8.
[15]凌永祥,陈明逵.计算方法教程.西安:西安交通大学出版社,2005.Ling Y X,Chen M K.A Course in Computational Method(in Chinese).Xi′an:Xi′an Jiaotong University Press,2005.
[16]Ganley D C.A method for calculating synthetic seismograms which include the effects of absorption and dispersion.Geophysics,1981,46(8):1100-1107.
[17]高静怀,杨森林,王大兴.利用VSP资料直达波的包络峰值处瞬时频率提取介质品质因子.地球物理学报,2008,51(3):853-861.Gao J H,Yang S L,Wang D X.Quality factor extraction using instantaneous frequency at envelope peak of direct waves of VSP data.Chinese J.Geophys.(in Chinese),2008,51(3):853-861.
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