VTI介质角度域Kirchhoff叠前时间偏移方法
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摘要
为了支持VTI介质下的振幅随偏移距/入射角变化(AVO/AVA)技术,提出一种基于射线追踪的VTI介质角度域Kirchhoff叠前时间偏移方法。从VTI介质反射波时距关系出发,通过稳健的射线追踪算法建立反射走时和界面上入射角的数值表,进而估算射线路径对应的双程走时及入射角,利用脉冲响应叠加方法实现叠前时间偏移,得到构造图像和角度域共成像点道集。由于在振幅加权因子求取时考虑射线弯曲效应的影响,因此成像保幅性更好。所提方法获得的角度域共成像点道集同相轴平直,且有效入射角度范围更宽,有利于后续的AVO/AVA或反演处理。理论模型合成数据和实际地震资料测试结果展示了方法的优越性与实用性。
An angle-domain Kirchhoff prestack time migration approach in VTI media based on ray-tracing was presented to provide more powerful supports for AVO/AVA technique.Starting from the relationship between travel time and path length of the reflection waves in VTI media,a robust ray-tracing algorithm is developed to construct the numerical table for the travel time and incidence angle of the reflection waves on the interfaces,and then the two-way travel time and incident angle corresponding to the ray path can be estimated.As the result of a prestack time migration by using the impulse response superposition method,the structural image and the angle domain common image gathers can be obtained.During prestack time migration,impulse responses are stacked to obtain the migrated profile and angle-domain common-image gathers.This imaging method preserves the amplitude better than the traditional methods,because it includes ray bending in the calculations of the weighting factor for amplitude preserving.The angle-domain common image gathers of this method have straight in-phase axis and a wide range of the effective incidence angle,which is beneficial to the subsequent AVO/AVA and inversion processing.The synthetic and real data tests demonstrate the validity of this approach.
An angle-domain Kirchhoff prestack time migration approach in VTI media based on ray-tracing was presented to provide more powerful supports for AVO/AVA technique.Starting from the relationship between travel time and path length of the reflection waves in VTI media,a robust ray-tracing algorithm is developed to construct the numerical table for the travel time and incidence angle of the reflection waves on the interfaces,and then the two-way travel time and incident angle corresponding to the ray path can be estimated.As the result of a prestack time migration by using the impulse response superposition method,the structural image and the angle domain common image gathers can be obtained.During prestack time migration,impulse responses are stacked to obtain the migrated profile and angle-domain common-image gathers.This imaging method preserves the amplitude better than the traditional methods,because it includes ray bending in the calculations of the weighting factor for amplitude preserving.The angle-domain common image gathers of this method have straight in-phase axis and a wide range of the effective incidence angle,which is beneficial to the subsequent AVO/AVA and inversion processing.The synthetic and real data tests demonstrate the validity of this approach.
引文
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[10]DOUMA H M,VAN DER BAAN M.Rational interpola-tion of qP-traveltime fpr semblance-based anisotropy es-timation in layered VTI media[J].Geophysics,2008,73(4):D53-D62.
[11]田玥,陈晓非.水平层状介质中的快速两点间射线追踪方法[J].地震学报,2005,27(2):147-154.TIAN Yue,CHEN Xiao-fei.A rapid and accurate two-point ray tracing method in horizontally layered velocitymode1[J].Acta Seismologica Sinica(in Chinese),2005,27(2):147-154.
[12]BLEISTEIN N,COHEN J K,HAGIN F G.Two andone-half dimensional Born inversion with an arbitraryreference[J].Geophysics,1987,52(1):26-36.
[13]SCHLEICHER J,TYGEL M,HUBRAL P.3-D trueamplitude finite-offset migration[J].Geophysics,1993,58:1112-1126.
[14]LEE S,KING D,LIN S.Efficient true-amplitudeweights in Kirchhoff time migration[J].SEG Expand-ed Abstracts,2004,23:1089-1092.
[15]EKREN B O,URSIN B.True-amplitude frequency-wavenumber constant-offset migration[J].Geophysics,1999,64(3):915-924.
[16]LUMLEY D E,CLAERBOUT J F,BEVC D.Anti-aliased Kirchhoff 3-D migration[J].SEG ExpandedAbstracts,1994,13:1282-1285.
[2]SILIQI R,BOUSQUIE N.Anelliptic time processingbased on a shifted hyperbola approach[J].SEG Ex-panded Abstracts,2000,19:2245-2248.
[3]FOMEL S.On anelliptic approximations for qP velocitiesin VTI media[J].Geophysical Prospecting,2004,52(3):247-259.
[4]ZHENG Y.Seismic azimuthal anisotropy and fracture a-nalysis from PP reflection data[D].Calgary:Universityof Calgary,2006.
[5]WALDEN A T.Making AVO sections more robust[J].Geophysical Prospecting,1991,39,(7):915-942.
[6]PEREZ G,MARFURT K J.Improving lateral and verti-cal resolution of seismic images by correcting for waveletstretch in common-angle migration[J].Geophysics,2007,72(6):C95-C104.
[7]ZHANG Y,GRAY S,YOUNG J.Exact and approximateweights for Kirchhoff migration[J].SEG Expanded Ab-stracts,2000,19:1036-1039.
[8]DELLINGER J A,GRAN S H,MURPHY G E,et al.Efficient 2.5-D true-amplitude migration[J].Geophys-ics,2000,65:943-950.
[9]程玖兵,王楠,马在田.表驱三维角度域Kirchhoff叠前时间偏移成像方法[J].地球物理学报,2009,52(3):792-800.CHENG Jiu-bing,WANG Nan,MA Zai-tian.Table-driv-en 3-D angle domain imaging approach for Kirchhoff pres-tack time migration[J].Chinese J Geophys(in Chi-nese),2009,52(3):792-800.
[10]DOUMA H M,VAN DER BAAN M.Rational interpola-tion of qP-traveltime fpr semblance-based anisotropy es-timation in layered VTI media[J].Geophysics,2008,73(4):D53-D62.
[11]田玥,陈晓非.水平层状介质中的快速两点间射线追踪方法[J].地震学报,2005,27(2):147-154.TIAN Yue,CHEN Xiao-fei.A rapid and accurate two-point ray tracing method in horizontally layered velocitymode1[J].Acta Seismologica Sinica(in Chinese),2005,27(2):147-154.
[12]BLEISTEIN N,COHEN J K,HAGIN F G.Two andone-half dimensional Born inversion with an arbitraryreference[J].Geophysics,1987,52(1):26-36.
[13]SCHLEICHER J,TYGEL M,HUBRAL P.3-D trueamplitude finite-offset migration[J].Geophysics,1993,58:1112-1126.
[14]LEE S,KING D,LIN S.Efficient true-amplitudeweights in Kirchhoff time migration[J].SEG Expand-ed Abstracts,2004,23:1089-1092.
[15]EKREN B O,URSIN B.True-amplitude frequency-wavenumber constant-offset migration[J].Geophysics,1999,64(3):915-924.
[16]LUMLEY D E,CLAERBOUT J F,BEVC D.Anti-aliased Kirchhoff 3-D migration[J].SEG ExpandedAbstracts,1994,13:1282-1285.
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