近地表速度变化对地震波传播的影响
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摘要
地表起伏和近地表速度变化是影响地震波传播的两个重要因素。采用基于坐标变换的起伏地表弹性波正演模拟方法,对纵向变速、横向变速、随机变速等一系列速度模型进行了正演数值模拟,分析了起伏地表情况下近地表速度的不同变化对正演模拟记录的影响,得出近地表变速带厚度较薄、纵向层状变速明显、横向块状变速剧烈以及介质速度随机变化较大时都会导致噪声严重、模拟记录信噪比变低的结论。
Rugged surface and velocity variation in near-surface are two important factors that impact seismic wave propagation. With transformation of rugged topographic coordinate, we carried out forward numerical simulation on vertically variable velocity model, horizontally variable velocity model, and randomly variable velocity model, and analyzed the effect of velocity variation in near surface on the results of simulation. It is concluded that the thin variable velocity layer, significant layering variations of velocity, sharply bulky lateral variations of velocity, and large random velocity variation will all result in records of serious noises and low signal-to-noise ratio.
Rugged surface and velocity variation in near-surface are two important factors that impact seismic wave propagation. With transformation of rugged topographic coordinate, we carried out forward numerical simulation on vertically variable velocity model, horizontally variable velocity model, and randomly variable velocity model, and analyzed the effect of velocity variation in near surface on the results of simulation. It is concluded that the thin variable velocity layer, significant layering variations of velocity, sharply bulky lateral variations of velocity, and large random velocity variation will all result in records of serious noises and low signal-to-noise ratio.
引文
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2张兵.起伏地表及低降速带对反射波的影响[J].勘探地球物理进展,2007,30(5):348~351
3李振春,安琪,马光凯,等.基于共聚焦点技术的起伏地表基准面重建[J].勘探地球物理进展,30(5):373~376
4董良国,郭小玲,吴晓丰,等.起伏地表弹性波传播有限差分法数值模拟[J].天然气工业,2007,27(10):38~41
5董良国.复杂地表条件下地震波传播数值模拟[J].勘探地球物理进展,2005,28(3):187~194
6姚姚,奚先.随机介质模型正演模拟及其地震波场分析[J].石油物探,2002,41(1):31~36
7Tessmer E,Kosloff D,Behle A.Elastic wave propaga-tion si mulation in the presence of surface topography[J].Geophysical Journal International,1992,108(2):621~632
8Hesthol m S,Ruud B.2D finite-difference elastic wave modeling including surface topography[J].Geophysical Prospecting,1994,42(5):371~390
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