初至旅行时层析反演近地表模型精度分析
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摘要
为了提高初至旅行时层析反演近地表速度模型的精度,改善静校正效果,本文研究了激发井深以及约束速度对反演精度的影响。通过建立典型低降速层近地表模型,首先对比分析零井深、井深穿过低速层和井深穿过降速层三种情况下,射线穿过网格的特性及激发井深在低速层以下时,最小约束速度对低速层反演效果的影响;其次利用井口时间确定最小约束速度,并提出了辅助点激发确定最小约束速度的新方法;最后应用于合成与实际地震数据,提高了反演精度。
In order to improve the inversion accuracy of near-surface model inversed by first break traveltime tomography,and then to enhance static corrections more effective,the paper discusses the impact of source depth and constraint velocity on the inversion accuracy.Based on typical synthetic near-surface model,we adopt analysis on the characteristic of ray paths from the source on the surface,the source below weathering and the source below sub-weathering.We discuss the impact of the minimum constraint velocity on the inversion of the weathering when source depth is below weathering.Furthermore,uphole time is involved to determine the minimum constraint velocity and a new method to determine the minimum constraint velocity,called auxiliary source,is also described.Finally the method is applied both to synthetic data and real seismic data and results show that the inversion accuracy is improved.
In order to improve the inversion accuracy of near-surface model inversed by first break traveltime tomography,and then to enhance static corrections more effective,the paper discusses the impact of source depth and constraint velocity on the inversion accuracy.Based on typical synthetic near-surface model,we adopt analysis on the characteristic of ray paths from the source on the surface,the source below weathering and the source below sub-weathering.We discuss the impact of the minimum constraint velocity on the inversion of the weathering when source depth is below weathering.Furthermore,uphole time is involved to determine the minimum constraint velocity and a new method to determine the minimum constraint velocity,called auxiliary source,is also described.Finally the method is applied both to synthetic data and real seismic data and results show that the inversion accuracy is improved.
引文
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[11]Den Z Wet al.The application of uphole ti meτinhigh precision seismic prospecting.SEG TechnicalProgram Expanded Abstracts,2007,26:1074~1078
[12]李宇,杨德义,邓辉等.旅行时差值曲线方法在时间项反演中的应用.中国煤炭地质,2009,21(2):46~49Li Yu,Yang De-yi,Deng Hui et al.Application oftravel-ti me difference curve method in ti me-termin-version.Coal Geology of China,2009,21(2):46~49
[2]Ali I K.Initial velocity model construction of seismictomography in near-surface applications.Journal ofApplied Geophysics,2009,67(1):52~62
[3]Noble M et al.High-performance 3D first-arrivaltravelti me tomography.The Leading Edge,2010,29(1):86~93
[4]刘玉柱,董良国,夏建军.初至波走时层析成像中的正则化方法.石油地球物理勘探,2007,42(6):682~685,698Liu Yu-zhu,Dong Liang-guo and Xia Jian-jun.Nor-malized approach in tomographic i maging of firstbreaks travel ti me.OGP,2007,42(6):682~685,698
[5]刘玉柱,董良国.初至波层析影响因素分析.石油地球物理勘探,2007,42(5):544~553Liu Yu-zhu and Dong Liang-guo.Analysis of influencefactor of first-breaks tomography.OGP,2007,42(5):544~553
[6]刘玉柱,董良国,李培明等.初至波菲涅尔体地震层析成像.地球物理学报,2009,52(9):2310~2320Liu Yu-zhu,Dong Liang-guo,Li Pei-ming et al.Fresnel volume tomography based on first breaks.Chinese J Geophys,2009,52(9):2310~2320
[7]李庆忠.走向精确勘探的道路.北京:石油工业出版社,1994
[8]Sherif R E,Geldart L P.Exploration Seismology.Cambridge Univ Press,1995
[9]Toshiki Wet al.I mprovement in accuracy of seismictravelti me tomography by adding a priori informationas constraints on velocity reconstruction.J Soc MatSci,Japan,1995,44:874~879
[10]李宇,杨德义,闫培等.一种快速建立层析反演初始模型的方法.煤田地质与勘探,2009,37(6):67~70Li Yu,Yang De-yi,Yan Pei et al.A method of quicklycreating an initial model in tomography inversion.Coal Geology&Exploration,2009,37(6):67~70
[11]Den Z Wet al.The application of uphole ti meτinhigh precision seismic prospecting.SEG TechnicalProgram Expanded Abstracts,2007,26:1074~1078
[12]李宇,杨德义,邓辉等.旅行时差值曲线方法在时间项反演中的应用.中国煤炭地质,2009,21(2):46~49Li Yu,Yang De-yi,Deng Hui et al.Application oftravel-ti me difference curve method in ti me-termin-version.Coal Geology of China,2009,21(2):46~49
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