逆时偏移中几种角度域成像条件噪声压制效果分析

Analysis of noise suppression effect of several angle imaging conditions in reverse time migration

逆时偏移使用双程波动方程进行波场外推,含有各个方向角度的波场,成像精度高,但这也给成像结果带来了强振幅的低频噪声,严重影响成像质量.角度域成像条件通过对角度或者方向信息进行筛选来有效的压制低频噪声,是逆时偏移中常用的低频噪声压制方法.本文首先分析了逆时偏移中低频噪声产生的机制,并给出了几种能够有效压制低频噪声的角度域成像条件,结合数值实验对几种角度域成像条件进行试算和比较,数值算例表明了几种角度域成像条件对于低频噪声压制的有效性.

RTM（ Reverse Time Migration） uses two-way wave equation to extrapolate the wave field,which has wavefield with all directions and angles,as well as high imaging precision. But it also brings low-frequency noise with strong amplitude to the imaging result and affects the image quality seriously. Angle domain imaging conditions suppress low-frequency noise by effectively filtering the angle or direction information. It is often used in RTM lowfrequency noise suppression. In this paper,we first analyze the principle of low-frequency noise generation in RTM and then gives several kinds of angle-domain imaging conditions that can effectively suppress the low-frequency noise. Through the calculation and comparison of several angles imaging conditions in numerical experiments,we can see the effectiveness of these methods.