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作者提出一种半递归克希霍夫偏移算法,该法通过波动方程拉半和克希霍夫偏移取得复杂构造的精确图像。该方法之所以颇为成功的原因在于:它把复杂的速度构造划分成若干小的深度区段,区段划分以易于旅行时计算并能对应高能波至为原则。上述区段内计算得到的旅行时首先用于成像,然后再用于把整个观测系(炮点和检波器)向下推延至下区段的边界。由这一方法获得的图像与由炮点剖面偏移法所获得的图像不相上下,但计算费用却可以降下来。因为旅行时是在很小的深度范围内计算的,所以不会产生焦散波、首波和多次波的不利影响。原则上,这种方法仅需要与标准偏移法相同的旅行时计算次数。以此法对Marmous数据集进行的试验产生了优异的结果。
The authors propose a semi-recursive Kirchhoff migration algorithm, which obtains complex images of complex structures by pulling the half-wave and Kirchhoff offsets by the wave equation. The reason why the method is quite successful is that it divides the complicated velocity structure into several small depth sections, and the section division is based on the principle of easy calculation when traveling and corresponding to high energy wave. The calculated travel time in the above section is first used for imaging and then for the entire observation system (shot and detector) to be pushed down to the lower section boundary. The image obtained by this method is comparable to the one obtained by the shot-point migration, but the computational cost can be reduced. Because travel is calculated in a small depth range, there is no adverse effect of caustic, first and multiples waves. In principle, this method requires only the same number of travel time calculations as the standard deviation method. Experiments with the Marmous dataset in this way yielded excellent results.