声波和弹性波叠后逆时深度偏移

ACOUSTIC-AND ELASTIC-WAVE POST-STACK REVERSE-TIME DEPTH MIGRATION

对比声波和弹性波叠后逆时深度偏移的成像效果,从计算波动理论出发,采用凹陷模型制作了基于爆炸反射界面原理的零偏移距剖面。并根据零时间逆时成像条件,制作了较高精度的声波、弹性波叠后逆时成像剖面。逆时延拓数值试算表明,采用两种方法均能恢复出准确的地质界面,其中声波在倾斜界面情况下与实际地质模型有所偏移,没有准确实现地震波场归位;而弹性波垂直分量得到了准确成像,倾斜界面清晰,而且垂直分量直接显示出断点和倾斜界面位置,弥补了声波深度成像的不足。

In this study,an imaging effect of acoustic-wave post-stack reverse-time depth migration is compared to that of elastic-wave post-stack reverse-time depth migration;and then a zero-offset section based on a principle of exploding reflection interface is developed by a sag model;at last,the acoustic-and elastic-wave post-stack reverse-time imaging section with a higher accuracy is also developed.It is shown from a continuation numerical calculation that two methods may recover an accurate geological interface.However,for acoustic-wave method,there is a little migration from a real geological model under a slant interface and a zero wave field homing can not realized very precisely.For elastic-wave method,its vertical component may obtain an accurate imaging and its slant interface can be seen very clearly;and the vertical component also shows directly both break point and slant-interface location in order to make up for acoustic-wave depth imaging.