快速三维相位移加插值偏移

Fast 3-D migration using phase shift plus interpolation

本文采用相位移加插值的方法实现了三维一步法偏移。在三维偏移计算中，对向下延拓的其子进行了变形，故允许使用大延拓步长向下延拓，允许成像过程中使用FFT方法。此法可根据地层的变化情况自动调整连续延拓的步长，提高了计算效率。相移插值方法用于三维一步法偏移不存在偏移算子在x，y方向分裂引起的三维偏移归位误差问题，且无频散现象，能适用于纵横向变速情况。实例表明，本方法是一种适合陡倾角、复杂地质构造归位的三维一步法偏移成像技术。

One-pass 3-D migration can be achieved by using phase shift plus interpolation. The deformation of downward continuation operator in 3-D migration allows the uses of big step size in downward continuation and fast Fourier transform in image. What is more, the continuation step size can be automatically adjusted according to formation variation, thus greatly improving the computation efficiency. The application of phase shift plus interpolation to one-pass 3-D mig-ration causes neither the frequency dispersion nor the error that is incurred by migration operator splitting in x-y direction; therefore, the method is applicable to the situation where velocity varies vertically and laterally. It is illustrated that the method is one-pass3-D migration technique that can nicely cope with complicated steep geology structures.