DOUBLE SQUARE ROOT EQUATION 3D PRESTACK DEPTH MIGRATION
双平方根方程三维叠前深度偏移

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.