实际数据的弹性波有限元反时偏移结果

REAL DATA RESULTS OF THE FINITE ELEMENT REVERS-TIME ELASTIC WAVE MIGRATION

美国哥伦比亚大学应用地球物理实验室

利用有限元和反时外推算法,在过去的二年中,我们发展了弹性波叠前有限元反时偏移方法;并对有偏移距的合成数据进行了偏移。作为对在过去二年中所写的文章的姐妹篇,本文给出了实际数据的弹性波有限元反时偏移结果。 本文所使用的实际数据是具有两个分量的共炮点(CSP)道集。偏移中所使用的速度V_p和V_a是由均方根(RMS)速度分析和Dix公式确定的。偏移前对实际数据进行了预处理。在偏移深度剖面上,偏移成像较好地勾划出反射点。而且,将水平与垂直分量偏移剖面结合起来的“调整场”偏移深度剖面,由于消除了各自分量的偏移剖面上的背景噪音,显示出更加清晰的像。

By means of the finite element method and reverse-time extrapolation, we have developed the prestack finite element reverse-time migration method for elastic waves, and have applied it to migrate offset synthetic data in the last two years. As a companion to our last two years papers, this paper presents the real data migration results using the finite element reverse-time elastic wave migration method.The real data used in this paper are two-component common-shotpoint( CSP) gathers. The velocities Vp and Vs used in migration were determined from root-mean-square (RMS) velocity analysis and Dix’ s formula. The preprocessing of the real data was applied before migration . On the migrated depth sections, migration images well delineate the reflectors. Moreover, the migrated depth section of "modified field",which combines the vertical and the horizontal component migrated sections ,provides a clearer image display due to the elimination of background noise in each individual component migrated section.