数据驱动型多次波衰减方法的研究
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摘要
在油气田勘探过程中,多次波的存在往往会直接影响地质构造的解释程度.鉴于自由界面的反射系数一般都远远大于地层的反射系数,与之相关多次波具有更强的能量,更多的宽频带,本文聚焦于与表面相关多次波的模拟与衰减.表面多次波的衰减可以表述为一种迭代的过程,其中MPI(Wang,2003)是一种全数据驱动型的多次波建模方法,它是通过迭代修正多次波模型从而预测出更为精确的多次波.MPI多次波建模方法的显著特征在于它减弱了对表面操作因子的依赖性,即在先验信息未知的情况下,仍可以依据地震数据而模拟出较为精确的多次波模型,这种方法的另一特征在于它不仅在时间域而且在相位和振幅域也可以模拟出多次波模型.根据实际地震数据的应用效果,表明在给定一个一般精度的去多次波结果的情况下,通过利用全数据驱动型迭代反演可以建立更为精确的多次波模型,然后再把它从原始地震数据中减去,从而更为有效地压制和衰减多次波场能量.
In the practical seismic profile multiple reflections tend to impede the task of even the experienced interpreter in deducing information from the reflection data.Surface multiples are usually much stronger,more broadband,and more of a problem than internal multiples because the reflection coefficient at the water surface is much larger than the reflection coefficients found in the subsurface.For this reason most attempts to remove multiples from marine data focus on surface multiples.A surface-related multiple attenuation method can be formulated as an iterative procedure.In this essay a fully data-driven approach which is called MPI —multiple prediction through inversion(Wang,2003) is applied to a real marine seismic data example.This is a pretty promising scheme for predicting a relative accurate multiple model by updating the multiple model iteratively,as we usually do in a linearized inverse problem.The prominent characteristic of MPI method lies in that it eliminates the need for an explicit surface operator which means it can model the multiple wavefield without any knowledge of surface,subsurface structures and a source signature.Another key feature of this scheme is that it can predict multiples not only in time but also in phase and in amplitude domain.According to the real data experiments it is shown that this scheme for multiple prediction can be made very efficient if a good initial estimate of the multiple-free data set can be provided in the first iteration.In the other core step which is multiple subtraction we use an expanded multi-channel matching filter to fulfil this aim.
In the practical seismic profile multiple reflections tend to impede the task of even the experienced interpreter in deducing information from the reflection data.Surface multiples are usually much stronger,more broadband,and more of a problem than internal multiples because the reflection coefficient at the water surface is much larger than the reflection coefficients found in the subsurface.For this reason most attempts to remove multiples from marine data focus on surface multiples.A surface-related multiple attenuation method can be formulated as an iterative procedure.In this essay a fully data-driven approach which is called MPI —multiple prediction through inversion(Wang,2003) is applied to a real marine seismic data example.This is a pretty promising scheme for predicting a relative accurate multiple model by updating the multiple model iteratively,as we usually do in a linearized inverse problem.The prominent characteristic of MPI method lies in that it eliminates the need for an explicit surface operator which means it can model the multiple wavefield without any knowledge of surface,subsurface structures and a source signature.Another key feature of this scheme is that it can predict multiples not only in time but also in phase and in amplitude domain.According to the real data experiments it is shown that this scheme for multiple prediction can be made very efficient if a good initial estimate of the multiple-free data set can be provided in the first iteration.In the other core step which is multiple subtraction we use an expanded multi-channel matching filter to fulfil this aim.
引文
[1]Weglein B.Multiple attenuation:an overview of recent ad-vances and the road ahead[J].The Leading Edge,1999,40~44.
[2]Fail J P,Grau G.Les filtres en eventail[J].Geophysical Pros-pecting,1963,11:131~163.
[3]Backus M M.Water reverberations-their nature and elimina-tion[J].Geophysics,1959,24:233~261.
[4]Wiggins J W.Attenuation of complex water-bottom multiplesby wave-equation-based prediction and subtraction[J].Geo-physics,1988,53:1527~1539.
[5]Verschuur D J,Berkhout A J,Wapenaar C P A.Adaptive sur-face-related multiple elimination[J].Geophysics,1992,57:1166~1177.
[6]Lu G C,Bjorn U,Jan L.Model-based removal of water-layermultiple reflections[J].Geophysics,1990,64:1816~1827.
[7]Wang Y.Multiple prediction through inversion:A fully data-driven concept for surface-related multiple attenuation[J].Geophysics,2004,69:547~553.
[8]Berkhout A J.Seismic migration:Imaging of acoustic energyby wavefield extrapolation,second edition:Elsevier SciencePubl.Co.Inc.,1982.
[9]Verschuur D J.Surface-related multiple elimination:an inver-sion approach:Ph.D.thesis.Delft University of Technolo-gy,1991.
[10]Wang Y.Seismic trace interpolation in the f-x-y domain[J].Geophysics,2002,67:1232~1239.
[11]Wang Y.Multiple prediction through inversion:Theoreticaladvancements and real data application[J].Geophysics,2007,72:33~39.
[12]Berkhout A J,Verschuur D J.Estimation of multiple scatter-ing by iterative inversion,Part I:Theoretical considerations[J].Geophysics,1997,62:1586~1595.
[13]Verschuur D J,Prein R J.Multiple removal results fromDelft University[J].The Leading Edge,1999,86~91.
[14]Panos G K,Verschuur D J.Surface-related multiple elimina-tion on land seismic data-Stretegies via case studies[J].Geo-physics,2000,65:719~734.
[15]Wang Y.Seismic trace interpolation in the f-x-y domain[J].Geophysics,2002,67:1232~1239.
[16]Wang Y.Multiple subtraction using an expanded multichan-nel matching filter[J].Geophysics,2003,68:346~354.
[2]Fail J P,Grau G.Les filtres en eventail[J].Geophysical Pros-pecting,1963,11:131~163.
[3]Backus M M.Water reverberations-their nature and elimina-tion[J].Geophysics,1959,24:233~261.
[4]Wiggins J W.Attenuation of complex water-bottom multiplesby wave-equation-based prediction and subtraction[J].Geo-physics,1988,53:1527~1539.
[5]Verschuur D J,Berkhout A J,Wapenaar C P A.Adaptive sur-face-related multiple elimination[J].Geophysics,1992,57:1166~1177.
[6]Lu G C,Bjorn U,Jan L.Model-based removal of water-layermultiple reflections[J].Geophysics,1990,64:1816~1827.
[7]Wang Y.Multiple prediction through inversion:A fully data-driven concept for surface-related multiple attenuation[J].Geophysics,2004,69:547~553.
[8]Berkhout A J.Seismic migration:Imaging of acoustic energyby wavefield extrapolation,second edition:Elsevier SciencePubl.Co.Inc.,1982.
[9]Verschuur D J.Surface-related multiple elimination:an inver-sion approach:Ph.D.thesis.Delft University of Technolo-gy,1991.
[10]Wang Y.Seismic trace interpolation in the f-x-y domain[J].Geophysics,2002,67:1232~1239.
[11]Wang Y.Multiple prediction through inversion:Theoreticaladvancements and real data application[J].Geophysics,2007,72:33~39.
[12]Berkhout A J,Verschuur D J.Estimation of multiple scatter-ing by iterative inversion,Part I:Theoretical considerations[J].Geophysics,1997,62:1586~1595.
[13]Verschuur D J,Prein R J.Multiple removal results fromDelft University[J].The Leading Edge,1999,86~91.
[14]Panos G K,Verschuur D J.Surface-related multiple elimina-tion on land seismic data-Stretegies via case studies[J].Geo-physics,2000,65:719~734.
[15]Wang Y.Seismic trace interpolation in the f-x-y domain[J].Geophysics,2002,67:1232~1239.
[16]Wang Y.Multiple subtraction using an expanded multichan-nel matching filter[J].Geophysics,2003,68:346~354.
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