中文摘要：

从起伏地表直接进行叠前逆时偏移是解决地表起伏大并且地下构造复杂这种双复杂结构地区成像问题的有力工具．本文给出了起伏地表直接进行叠前逆时偏移的实现过程，针对有限差分方法处理起伏地表自由边界条件的复杂性，采用了一种简化的自由边界条件，避免了大量的逻辑判断，在此基础上，采用图形处理器（Graphic Processing Unit，简称GPU）将算法加速，比传统的CPU计算速度提高了一个数量级．文中对理论模型进行了计算，并与起伏地表直接进行单程波叠前偏移方法做比较，结果表明：起伏地表叠前逆时偏移有效突破了成像倾角限制，对起伏地表浅层构造以及地下高陡构造成像效果显著提高．关于逆时偏移成像噪音去除以及存储量等问题，笔者已有文章介绍，本文将不再涉及．

英文摘要：

Pre-stack reverse time migration （RTM） for rugged topography is a very useful tool for seismic imaging in the areas with rugged surface topography andcomplex subsurface structures. In this paper, we illustrate the implementation process of RTM for rugged topography. For the difficulty in dealing with the rugged free boundary condition with the finite difference method, we employ a simplified boundary condition which can avoid the abundant logical judgment. On this basis, we use the Graphic Processing Unit （GPU） algorithm to accelerate RTM and get an order of magnitude higher speedup ratio compared to the traditional CPU algoritm. The tests onsynthetic data and the comparison with the pre-stack one-way wave method for rugged topography prove that RTM does not have the imaging dip limit, and the imaging results for near surface structures and subsurface steep structures are significantly improved. The problems of imaging noise removal and massy memory demand of RTM have been stated previously and will not be discussed in this paper.