相移插值法偏移中一种新的变延拓步长方法

在叙述相移插值法波动方程偏移原理、对该偏移过程中的波场外推公式及最终成像方程进行适当的改进变形后,重新标定了向下外推算子,使得成像过程可借助于 FFT 来完成,并给出了一种不同于时间域内插的新的变延拓步长的方法。本方法与传统的相移插值法偏移中时间域内插值法变延拓步长相比,向下外推步长可远远大干地震波视波长的四分之一,从而满意地解决了相位插值偏移算法效率低的问题。文中给出的理论模型计算与实际煤田及陡倾角地震数据偏移处理的结果表明:本方法是一种快速经济的,适合于陡倾角、复杂地质构造归位的 f-k 域偏移成像技术。

A new varied continuation step method in seismic migration by phase shift plus interpolation.

The principle of wave equation migration using phase shift plus interpola- tion is described briefly.Wave field extrapolation formula in such migration and final imaging equation are properly modified,with downward extrapolation oper- ator redefined,so that the imaging can be achieved by using fast Fourier trans- form(FFT).A new varied continuation step method is given which is different from usual one in time domain.The new method,which is different from usual varied continuation step method for time domain interpolation in phase shift plus interpolation migration,uses the downward extrapolation continuation step much longer than a quarter of an apparent wave length;therefore,the efficiency of such seismic migration is improved satisfactorily. The processing results of theoretical model,coal field and high dip seismic data show that this new method is a f-k domain migration technique which is e- conomic and suitable to the seismic data collected from the area where there are high dip formations and complicated geological structures.