基于抛物线方程的坐标拉伸τ-p变换的P-P、P-SV波分离

Separating P—SV wave from P—P wave by coordinate stretch τ—p transform based on parabolic equation

分离P-P波和P-SV波最常用的是τ-p变换法,但是在τ-p域中,P-P波和P-SV波常有重叠部分,不能很好分离。地震勘探中,当炮检距小于界面深度时,P-P波和P-SV波的时距曲线方程都可近似为抛物线方程。针对这种情况,提出了一种基于抛物线方程的坐标拉伸τ-p变换的P-P、P-SV波分离方法,该方法首先对地震记录沿空间方向上进行坐标拉伸,再进行τ-p正变换,在τ-p域中分离P-P波和P-SV波,其次对P-P波和P-SV波分别进行τ-p反变换,实现P-P波和P-SV波的分离。与常规τ-p变换法对比分析表明,利用该方法能很好地将合成地震记录中的P-P波和P-SV波分离。

τ—p transform method is the most effective method for separating P—SV wave from P—P wave,but sometimes P—SV wave overlaps P—P wave and can not be separated completely in τ—p domain.When offset is shorter than interface depth in seismic exploration,the time-distance curve equations of P—SV wave and P—P wave can approximate to parabolic equations.Aiming at this situation,a method to separate P—SV wave from P—P wave by coordinate stretch τ—p transform based on parabolic equation is present.The authors process the seismic records by coordinate stretch along space direction and do τ—p transform at first,and then separate P—SV wave from P—P wave in τ—p domain,and inverse τ—p transform for P—SV wave and P—P wave respectively to separate P—SV wave from P—P wave finally.In contrast with normal τ—p transform,this method can separate P—SV wave from P—P wave completely and effectively.