地震叠前逆时偏移高阶有限差分算法及GPU实现

叠前逆时偏移技术是解决地震成像问题的有力工具,但由于计算量大、成像噪音以及存储量大等原因没有得到广泛的应用.本文给出了逆时偏移的实现过程,分析了高阶有限差分格式的稳定性与频散关系.针对叠前逆时偏移计算量大的问题,使用图形处理器(Graphic Processing Unit,简称GPU)实现算法加速,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,并与单程波偏移方法做比较,结果表明:叠前逆时偏移有效突破了成像倾角限制,对垂直断层、盐丘空腔内幕等特殊构造成像效果均有显著提高.本文尚未涉及成像噪音去除以及存储量等问题,笔者将另文阐述.

The algorithm of high order finite difference pre-stack reverse time migration and GPU implementation

Pre-stack reverse time migration (RTM) is a very useful tool for seismic imaging. But it has not been widely used because of the highly intensive computation cost, imaging noise and massy memory demand. In this paper, we illustrate the implementation process of RTM and analyze the stability condition and dispersion relation of finite difference (FD) method. For the problem of intensive computation cost, we use the Graphic Processing Unit (GPU) architecture to realize RTM and get an order of magnitude higher speedup ratio compared to the traditional CPU architecture. Compared to the one way wave equation migration methods, RTM does not have the imaging dip limit and the imaging effect is significantly improved. The test on vertical fault and BP models proves this conclusion. The problems of imaging noise removing and massy memory demand will be discussed in other papers.