复杂构造区叠加速度分析
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摘要
在地震勘探中,当目的层上覆地层存在速度横向剧烈变化时,基于双曲线动校公式中的叠加速度只是一种等效速度,而不是常规意义下的均方根速度。在地震数据处理中,用于目的层叠加成像的速度受这种速度横向变化的影响很大。若使共中心点道集内的反射同相轴校平后能够同相叠加,叠加速度则会出现一些低或高的异常。其原因是共中心点道集内远、近炮检距的射线穿过上覆地层的旅行时差随速度的横向变化而偏离双曲线变化趋势,从而使正常动校时差发生改变。因此以共中心点道集反射同相轴校平为准则求取的叠加速度与均方根速度之间的关系非常复杂。本文试图通过理论模型和实际数据对这一现象进行分析,加深对这一问题的认识。
During the seismic exploration, the stack velocity based on hyperbolic NMO formula is equivalent velocity, not mean-square-root (MSR) velocity in common meaning when the velocities in overburdens of target laterally change rapidly. In seismic data processing, the velocities used for stack imaging of targets are badly affected by this kind of lateral variation of velocities. In order to in-phase stack of aligned reflection events on CMP gathers, the stack velocities may have some higher or lower anomalies. The reason is that the moveout,the rays crossing overburdens at near and far offsets on CMP gathers,deviates from hyperbolic tendency because of the lateral change of velocities, making the NMO change. So,the relationship between the stack velocity taking aligning the reflection events on the CMP gathers as a law and MSR velocity is very complicated, the paper tries to analyze this phenomenon by theoretical models and real data, deepening the knowledge of the issue.
During the seismic exploration, the stack velocity based on hyperbolic NMO formula is equivalent velocity, not mean-square-root (MSR) velocity in common meaning when the velocities in overburdens of target laterally change rapidly. In seismic data processing, the velocities used for stack imaging of targets are badly affected by this kind of lateral variation of velocities. In order to in-phase stack of aligned reflection events on CMP gathers, the stack velocities may have some higher or lower anomalies. The reason is that the moveout,the rays crossing overburdens at near and far offsets on CMP gathers,deviates from hyperbolic tendency because of the lateral change of velocities, making the NMO change. So,the relationship between the stack velocity taking aligning the reflection events on the CMP gathers as a law and MSR velocity is very complicated, the paper tries to analyze this phenomenon by theoretical models and real data, deepening the knowledge of the issue.
引文
[1]R E谢里夫,L P吉尔达特.勘探地震学.北京:石油工业出版社,1999,385~394
[2]Yil maz Zdogan.Data Analysis,2001,312~318
[3]马海珍等.地震速度场建立与变速构造成图的一种方法.石油地球物理勘探,2002,37(1):53~59
[4]邵雨等.模型速度建场方法的应用研究.石油地球物理勘探,2003,38(6):675~679
[2]Yil maz Zdogan.Data Analysis,2001,312~318
[3]马海珍等.地震速度场建立与变速构造成图的一种方法.石油地球物理勘探,2002,37(1):53~59
[4]邵雨等.模型速度建场方法的应用研究.石油地球物理勘探,2003,38(6):675~679
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