中文摘要：

三维起伏地表条件下的地震波走时计算技术是研究三维起伏地表地区很多地震数据处理技术的基础性工具．为了获得适应于任意三维起伏地表且计算精度高的走时算法，提出三维不等距迎风差分法．该方法采用不等距网格剖分三维起伏地表模型，通过在迎风差分格式中引入不等距差分格式、Huygens原理及Fermat原理来建立地表附近的局部走时计算公式，并通过在窄带技术中设定新的网格节点类型来获得三维起伏地表条件下算法的整体实现步骤．精度及算例分析表明：三维不等距迎风差分法具有很高的计算精度且能够适应于任意三维起伏地表模型．

英文摘要：

The traveltime computation scheme in a 3D undulating surface condition has a great significance to some 3D seismic data processing techniques in complex topographical regions. To obtain a traveltime computation algorithm that can treat the 3D complex topography with high accuracy and good flexibility, we present an upwind finite difference method with nonuniform grid spacing. We use the grid with nonuniform grid spacing for dividing the velocity model. For obtaining the local traveltime computation formulas, we synthetically introduce the finitedifference scheme with nonuniform grid spacing, Huygens principle and Fermat principle into the conventional upwind finite difference scheme. To build up the implementation steps, we propose a new narrow-band technique in complex topographical conditions by improving the conventional narrow-band technique. The accuracy analysis and an example show that the new method can treat any 3D complex topography problems with high accuracy.