基于角度滤波成像的最小二乘逆时偏移

在前人研究的基础上，首先分析了逆时偏移（RTM）中低频噪声的产生原因，通过波场数据得到的反射角信息构建逆散射成像条件，并与最小二乘逆时偏移（LSRTM）结合，发展了一种基于角度滤波成像的最小二乘逆时偏移方法（ALSRTM），从波动方程能量守恒方面分析了ALSRTM的可行性和保幅性。在实现算法的基础上，对SEG/EAGE二维盐丘模型的稀疏采集地震数据的成像结果表明：ALSRTM可彻底压制浅层构造的低频噪声，有效消除震源效应，在浅、中、深层均具有更好的保幅性。另外，相比常规LSRTM，ALSRTM对含有随机噪声的观测数据和含误差速度模型的适应性更强。

Least-squares reverse time migration based on the angular filtering imaging condition

On the basis of predecessors' researches,we first analyze the cause of the low frequency noise in the reverse time migration (RTM).Then we deduce the angular filtering imaging condition using the reflection angle information obtained from wavefield data,combine it with the least-square reverse time migration (LSRTM),and develop least-squares reverse time migration based on the angular filtering imaging condition (ALSRTM).The feasibility and amplitude of ALSRTM is analyzed with the energy conservation of wave equation.Numerical test on the international standard SEG-EAGE 2-D salt dome model validates our ALSRTM and proves that the ALSRTM can not only significantly suppress migration artifacts,but also has a better amplitude-preserved capacity compared with those results obtained with the conventional LSRTM.Besides,ALSRTM has a stronger adaptability than the conventional LSRTM in the presence of migration velocity errors.