变速的F—K偏移

F—K MIGRATION WITH VARIABLE VELOCITY

地质矿产部海洋地质综合研究大队

本文以变换的观点出发来讨论F—K偏移,通过虚速度时深变换的方法,使F—K偏移适应于速度有变化的情况。由于要处理的数据总是有限长的和离散化的,前者会引起端部的边界效应,后者可能产生假频现象,这就要求我们考虑在各个坐标系中所选用的采样间隔的大小、数据道延伸的长短、边界二端的补零道、网格和接头等一系列问题。本文讨论了与这些问题有关的参数意义和选择原则,适当地选取这些参数能提高处理的效率和改善剖面的质量。本文提供了用变速F—K偏移方法计算的模型和实例。计算结果说明变速F—K偏移具有处理效率高、适应于陡倾角偏移和用来做反偏移等特点。变速的F—K偏移对速度变化较敏感,在速度变化较迅速的情况下,建议进行速度光滑。

In this paper, the F-K migration was examined from the view-point of transformation. By dint of the time-depth transformation, the F-K migration was made suitable for the state of variable velocity. Because of the data needed to process was always finite in length and discre-tized, it may produce the boundary effects at the end point and bring about the alias as well. Hence, the terms following related to the coordinate sys- terns should be taken into account carefully and seriously: the sampling intervals, the length of data channels, the padding channels in both ends of the boundary as well as the grid and its connection. The meaning of the parameters concerned and the principle of their choice were discussed also. It has been proved that the efficiency of processing may be rised and the quality of the section may be improved as long as the parameters were selected properly and correctly.In this paper, the models and examples resulted from the variable velocity F-K migration were presented. This k f migration has been proven to be high processing efficiency and suitable for the large dip angle as well as the inversion calculation. Moreover, it is sensible for the variation of velocity. Hence, it would be better to have the velocity smoothed in case the velocity varied roughly.