相移波动方程偏移波数域吸收方法探讨

The research of the absorption of the phase shift wave equation migration in wave number domain

相移波动方程偏移因其算法精确且稳健成为地震勘探领域中重要的偏移处理方法。但在实际资料偏移处理中,相移偏移在边界容易产生严重的折返效应,为此前人采用了补零法和空间域吸收方法来克服这一问题。但补零法成倍增加了数据量,空间域吸收需要在空间域与波数域之间反复做傅氏变换,这两种方法都降低了相移偏移处理的效率,影响了相移偏移的广泛有效应用。本文提出一种波数域吸收方法,应用点脉冲比较了空间域与波数域吸收的效果,应用工程模型验证了在波数域吸收偏移的正确性。结果表明,在波数域对Kx加权同样可有效克服边界效应,由于相移偏移和波数滤波同在波数域进行,不用在每个延拓步长中做正反傅氏变换。因此,该方法可提高相移偏移处理的计算效率。

Phase shift wave equation migration has become one of the most important methods in seismic exploration area as its accuracy and stability in algorithm. It will generate wraparound at the edge of phase shift migration in processing, wherefore the predecessors used the zero fill and the spatial domain absorption to solve the problem. The zero fill increase multiply the amount of data and the spatial domain absorption need Fourier tr.ansform again and again between the spatial domain and waive number domain, both of them decrease the efficiency of the phase shift migration processing, and affect the phase shift migration of extensive and effective application. Wherefore, a absorption of the wave number domain method is offered, the absorption effect between the spatial domain and the wave number domain are compared by applying pulse, the exactness of absorption migration in wave number domain is verified by applying engineering simulation. The wraparound can be overcome also by weighting Kx in wave number domain. Because of the Phase shift migration and wave number filtering are processed in the wave number domain, do not have to do the positive and negative Fourier transform in each extension step, the computational efficiency of the phase shift migration processing can be improved. This article also pointed out that the change of the characteristics of the wave field caused by the wave number domain.