偏移速度误差引起的假象分析
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摘要
深度偏移剖面中的深度误差与速度误差并不相等,有时可以达到速度误差的两倍。从分析偏移速度误差带来的各种假象出发,对比分析了速度误差对叠后深度偏移和叠前深度偏移的影响,发现偏移剖面的深度误差仅与速度模型的误差有关系,与具体的偏移方法(叠后或叠前深度偏移)没有直接的关系;对一个复杂的透镜体模型进行了波动方程叠后正演和偏移计算,详细讨论了不同速度误差带来的各种假象,发现速度误差不仅会带来深度误差,而且会造成构造体的形态变化,下覆地层同向轴的扭曲,还可能引起地层同向轴的频率发生变化,给资料解释带来一定的假象。正确地认识这些假象,对于速度分析中检验速度模型的正确性以及地震资料解释都具有重要的意义。
Depth error in depth migration profile isn't equal to velocity error, sometimes it is twice as many as velocity error. To analyze the pseudo phenomena caused by migration velocity error, the authors of the paper study the depth error between post-stack migration and prestack migration caused by same velocity error, and it is the depth error of migration profile is only related to velocity error and there is not direct relation with methods of depth migration (post-stack migration or prestack migration). Then the numerical simulation of a complex lenticular body model with wave-equation modeling and migration is done, and it is pointed out that the velocity error could not only induce depth error, but also change the modality of construction and the deformation in phase axis in subjacent layers. Furthermore, it could change the frequency of reflective event. They are the pseudo phenomena caused by migration. To correctly identify them is very important for testing the correctness of velocity model and seismic data explanation.
Depth error in depth migration profile isn't equal to velocity error, sometimes it is twice as many as velocity error. To analyze the pseudo phenomena caused by migration velocity error, the authors of the paper study the depth error between post-stack migration and prestack migration caused by same velocity error, and it is the depth error of migration profile is only related to velocity error and there is not direct relation with methods of depth migration (post-stack migration or prestack migration). Then the numerical simulation of a complex lenticular body model with wave-equation modeling and migration is done, and it is pointed out that the velocity error could not only induce depth error, but also change the modality of construction and the deformation in phase axis in subjacent layers. Furthermore, it could change the frequency of reflective event. They are the pseudo phenomena caused by migration. To correctly identify them is very important for testing the correctness of velocity model and seismic data explanation.
引文
[1]Landa E,Keydar S.How far is the seismic image correct[J].The Leading Edge,1998,17(7):919-922.
[2]Zhu J M,Lines L,Gray S.Smiles and frowns in migration/velocity analysis[J].Geophysics,1998,63(4):1200-1209.
[3]Donald A H.Pitfalls in seismic interpretation:depth mi-gration artifacts[J].The Leading Edge,2000,19(9):1016-1017.
[4]Geophysics bright sports[J].The Leading Edge,2005,24(4):394-395.
[5]杨俊,贺振华,黄德济.速度模型对地震波场偏移成像的影响[J].物探化探计算技术,2006,28(2):113-116.
[6]Gazdag J F,Sguazzero P.Migration of seismic data by phase shift plus interpolation[J].Geophysics,1982,49(2):124-131.
[7]贺振华,熊晓军.等时叠加波动方程正演[J].物探化探计算技术,2005,27(3):194-198.
[8]Xiong X J,He Z H,Huang D J.One-way wave equation seis-mic prestack forward modeling with irregular surfaces[J].Applied Geophysics,2006,3(1):13-17.
[9]牟永光,裴正林.三维复杂介质地震数值模拟[M].北京:石油工业出版社,2005.
[10]贺振华.反射地震资料偏移处理与反演方法[M].重庆:重庆大学出版社,1989.
[2]Zhu J M,Lines L,Gray S.Smiles and frowns in migration/velocity analysis[J].Geophysics,1998,63(4):1200-1209.
[3]Donald A H.Pitfalls in seismic interpretation:depth mi-gration artifacts[J].The Leading Edge,2000,19(9):1016-1017.
[4]Geophysics bright sports[J].The Leading Edge,2005,24(4):394-395.
[5]杨俊,贺振华,黄德济.速度模型对地震波场偏移成像的影响[J].物探化探计算技术,2006,28(2):113-116.
[6]Gazdag J F,Sguazzero P.Migration of seismic data by phase shift plus interpolation[J].Geophysics,1982,49(2):124-131.
[7]贺振华,熊晓军.等时叠加波动方程正演[J].物探化探计算技术,2005,27(3):194-198.
[8]Xiong X J,He Z H,Huang D J.One-way wave equation seis-mic prestack forward modeling with irregular surfaces[J].Applied Geophysics,2006,3(1):13-17.
[9]牟永光,裴正林.三维复杂介质地震数值模拟[M].北京:石油工业出版社,2005.
[10]贺振华.反射地震资料偏移处理与反演方法[M].重庆:重庆大学出版社,1989.
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