格林函数高斯束逆时偏移

Reverse time migration with Gaussian beams based on the Green function

本文以Kirchhoff积分法偏移为基础,采用高斯束叠加积分表示的格林函数表示正反向延拓波场,并利用正反向延拓波场互相关成像条件得到地下成像结果。模型试算和实际资料处理结果表明:高斯束逆时偏移方法结合了射线类偏移方法的高计算效率和逆时波动方程偏移的高精度,能很好地处理焦散点、大倾角等成像问题,并且具有面向目标成像的能力。

We base on Kirchhoff integral for propagated wavefields to realize migration,and rely on the calculation of the Green functions for the classical wave equation by performing a summation of Gaussian beams for the direct and back propagated wavefield.The subsurface image is obtained by calculating the coherence between the direct and back-propagated wavefields.The model calculation and the real data verify that our method combines the advantages of the high computational speed of ray-based migration with the high accuracy of reverse-time wave-equation migration,which can overcome problems with caustics,yield good images of steep dips,and be readily extendible to target-oriented implementation.