中文摘要：

山地地区地下地质结构复杂，地表高差大，变化剧烈.目前该类地区地震勘探中主要的成像手段依然是Kirchhoff叠前时间偏移.但地表高程的剧烈变化使叠前时间偏移的基准面很难选择.本文在传统方法的基础上，提出了一种在浮动基准面上修正常规叠前时间偏移走时计算的叠前时间偏移方法，该方法能够很大程度上提高山地地区、特别是地表高差变化大地区的成像效果.本文还介绍了GPU 在叠前时间偏移上的应用，通过GPU 对叠前时间偏移的优化和实现，得出如下结论：应用单颗NVIDIA Tesla C1060 GPU 进行叠前时间偏移，相比应用主频2.5 GHz的单核CPU计算效率可提高70倍以上.

英文摘要：

The geological structure in the mountainous regions is quite complicated, and the elevation varies violently. At present, the main approach for seismic data imaging is the prestack Kirchhoff time migration, however, violent variation of surface elevation makes the datum plane selection of prestack time migration very difficult. This article proposed a new prestack time migration method through modifying the routine travel time computation, this method can greatly raise the imaging effect in mountainous region with obvious variation of surface elevation. In addition, this paper also introduced application of GPU in prestack time migration, by which the prestack time migration has been optimized and implemented, and the computation efficiency of single NVIDIA Tesla C1060 GPU can be more than 70 times faster than single core CPU with main frequency of 2.5 GHz when without the I/O problem.