地震相干偏移与数据自参照偏移的关系

Seismic interferometric migration and data-referenced-only migration

地震相干偏移和数据自参照偏移是最近几年发展起来的地震成像新方法,并且已在地震勘探研究领域开始应用.该方法在VSP<垂直地震剖面)中的应用尤其值得关注,因为它部分地解决了一些在地面反射地震方法中难以解决的问题.地震相干偏移是用地震数据的互相关处理后的数据进行偏移,而数据自参照偏移则不必在偏移前对数据进行互相关处理,而是通过记录数据中的两个不同部分波场的延拓来互相参照进行偏移.二者的优点都是在偏移运算中可以不考虑原始震源位置、激发时间以及地震波初始传播路径.本文从偏移成像的理论出发分析了这两类算法,发现二者在成像原理上是一致的.本文还通过一个二维VSP多次波偏移的数值模拟实验,比较和归纳了这两类算法在实际应用中的特点.

Seismic interferometric migration and data-referenced only migration are recently developed seismic migration methods that have found some new applications in seismic exploration. Especially in some VSP （Vertical Seismic Profiling） imaging applications, they have partially solved some problems that are very difficult to solve by using conventional surface seismic data. While the interferometric migration method migrates cross-correlated seismic data, the data-referenced-only migration method has no such apparent procedure. It extrapolates different parts of the recorded seismic wavefields and these extrapolated wavefields are referred to each other during imaging. Both methods have the merits that the original seismic source position, triggering time, and near-source properties can all be ignored for imaging. We analyze these two methods, and relate them to the same seismic migration theory. We also compare their results on a synthetic VSP multiples migration experiment, and discuss some of the practical issues of using these two methods.