提高波动方程偏移方法的精度和效率是我们目 前的研究课题之一,其主要问题是如何获得横向速度变化很大的介质中陡倾反射层的精确图像。本文提出一种改进后的偏移方法,它以串行相移算子和有限差分下行延拓算子为基础。由于采用了串行算子,我们称该方法为傅氏有限差分偏移(FFD偏移)。通过加上一有限差分校正项,我们试图对分步傅氏偏移法加以推广和改进。使其适于横向速度变化很大的介质。与目前采用的多数偏移法相似,我们也以单程波动方程 Improving the accuracy and efficiency of the wave equation migration method is one of our current research topics. The main problem is how to obtain the accurate image of the steep reflection layer in a medium with a large variation in lateral velocity. This paper presents an improved offset method, which is based on serial phase shift operator and finite difference downlink continuation operator. Due to the use of serial operators, we call this method the Fourier Finite Difference Offset (FFD Offset). By adding a finite difference correction term, we attempt to generalize and improve the Fractional Fourier Shift. Make it suitable for media with large changes in lateral velocity. Similar to most offset methods currently used, we also make one-way wave equations