一项以Eulerian高斯束地震波场算法为基础的、全局笛卡尔坐标系下的、直接基于复杂地表的、新的快速高斯束偏移技术对于解决复杂山地偏移质量不好甚至不成像的难题有着重要的理论和实际意义。为实现该技术，拟定如下创新方案：①采用分区局部自适应加密不等距双重网格剖分复杂地表模型；②将不等距差分格式和Kirchhoff积分算子与常规Eulerian高斯束相结合，计算复杂地表条件下的正反向延拓波场；③综合利用互相关成像条件、双重网格及多源偏移技术实现偏移算法，并全面提升算法的运算速度。如上方案的采用决定了该偏移技术具有能灵活稳定地适应复杂地表、对复杂构造成像精确、算法简洁且运算速度快等特色。. 项目拟定的研究内容、目标、方案及可行性分析均是在综合考虑过去两年评审专家的宝贵意见、Eulerian高斯束的各种优势、大量调研及试探性研究工作的结论之后提出的，因此其具有明显的可行性和创新性。

A new fast Gaussian beam migration technique based on the seismic wavefield computational scheme using Eulerian Gaussian beam directly from complex topography in a global Cartesian coordinate is of great theoretical significance and actual worth for solving the problems of the poor imaging quality or no imaging result. To establish this technique, the following innovative research schemes are formulated: ①Build the complex topography model using the local adaptive refinement grids with non-uniform grid spacing near surface; ②Calculate the direct and back propagated seismic wavefield in complex topography condition by combining the finite difference formulas in the non-uniform grids and Kirchhoff integral operator with the conventional Eulerian Gaussian beam method; ③Implement and accelerate the Eulerian Gaussian beam migration directly from complex topography by simultaneously using the cross correlation imaging condition, duality grid and multi-source migration techniques. For adopting the above schemes, the migration method presented here has the following advantages: the flexible and stable adaptability to the complex topography, the ability to produce an accurate image result for complex velocity structure, concise and fast, et al.. We propose the study content, objectives, schemes and feasibility analysis of this application by simultaneously adopting the precious comments sent from the evaluation experts of NSFC over the past two years, some advantages of Eulerian Gaussian beam, and some conclusions of our much investigative and tentative research works, so they are innovational and feasible.