二道递归滤波VSP波场分离方法

上行波和下行波的分离是垂直地震剖面(VSP)资料处理的重要环节之一。本文提出一种用二道递归滤波分离 VSP 波场的新方法。这种方法在假定地层为水平层状介质的前提下，从一维波动方程出发，导出了相邻两道 VSP 记录的上行波和下行波计算公式。由于该方法参与运算的记录只有两道，因此，可以在资料道数少而其他方法又无能为力的情况下把波场分开。方法允许不均匀的检波点距，且不存在空间假频现象和混波效应。理论模型试算和实际资料处理的结果表明，该方法是切实可行的。

Two-trace recursive filtering for separating VSP wave fields

One of the important steps in VSP data processing is to separate upgoing wave from downgoing wave.Here we present a new VSP wave field separation method using two-trace recursive filtering.On the assumption that the medium is horizontally layered,we use one dimen- sional wave equation to derive calculation formula for upgoing and downgoing waves of two adjacent VSP traces.This method,using two traces only,can separate the VSP wave fields which can not be sepa- rated by other methods in the case of few traces.This method allows nonuniform group intervals;besides it does not cause spatial aliasing and wave mixing.Both theory and practice prove the method really feasible.