双平方根方程三维叠前深度偏移

从双平方根（DSR）形式的波动方程出发，基于沉降观测概念和地震波扰动理论，介绍了深度域的DSR全偏移算子及共成像道集的生成方法. 根据三维地震数据的方位角特征，通过对全偏移算子的稳相近似，依次导出了适应于零方位角道集、Cross line共偏移距道集以及共偏移距矢量道集的偏移算子. 理论分析与合成数据的数值试验表明，DSR全偏移算子、共方位角偏移算子对介质速度变化的适应性很强，而其余两种偏移算子仅适用于缓变速情况.

DOUBLE SQUARE ROOT EQUATION 3D PRESTACK DEPTH MIGRATION

Starting from the double square root (DSR) based wave equation, and based on the survey-sinking concept and the perturbation theory, we introduce a prestack depth full migration operator and an approach to construct common imaging gathers (CIGs). Considering the azimuthal characteristics of 3D prestack data, three DSR migration operators for common azimuth sections, cross-line common offset sections and common offset vector sections are developed respectively by the stationary phase method. Among them the cross-line common offset migration is a theoretically new DSR-based method. The theoretic analysis and examples on synthetic datasets show that the full migration operator and common azimuth migration operator have good performance in the case of strong velocity variation, but the other two operators can work only when the velocity varies smoothly.