直接下延法波动方程叠前深度偏移

Direct continuation method based on wave equation for prestack depth migration

对于地表和地下地质条件复杂地区的地震资料偏移处理来说,由于现有的偏移方法大都假设激发点和检波点在同一个水平面上,因此给偏移结果带来了一定的影响。为此,探讨了直接从起伏地表开始的波动方程叠前深度偏移方法。简述了逐步-累加法和频率-空间域有限差分叠前深度偏移方法的基本原理,在此基础上提出了复杂地表和地下地质条件下的直接下延波动方程叠前深度偏移方法,该方法不受起伏地表条件的限制,对模拟层速度的适应性强。模型试算和实际资料试处理表明,该方法直接从起伏地表开始向下偏移,将波动方程基准面校正和叠前深度偏移有机地结合起来,既能对复杂构造精确成像,又能适应任何起伏地表条件。

Most of the existing migration methods assume that the shot point and detect points are on the same horizontal, which often affects the migration result to a certain extent in migration processing of seismic data in the area where the geological condition is complex. Therefore, the wave equation pre-stack depth migration, a method starting directly from the rolling surface, is discussed. The principle of step-to-step-accumulation method and frequency-spatial-domain finite difference prestack depth migration method is summarized. On the basis of this, the direct continuation method based on wave equation for prestack depth migration method is proposed for those areas where the geological conditions are complex The method isn't constricted by the rolling surface and is well a-daptable to the velocity of stimulated horizon. The calculation and practice show that the method not only can form high-resolution images for the area with complex geological condition, but also is well suitable for any rolling surface.