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对于二维陡倾斜地层，相位移延拓方法成像精度高、稳定性好、速度快，但难以适应速度的横向变化；频率、空间域的有限差分算法简单、稳定性好、能适应速度的纵、横向变化，但成像精度低、运算速度慢；而用快速的45°有限差分法与相位移延拓法相结合，则能使整个延拓过程既适应速度的纵、横向变化，又能够使得陡倾角地层精确归位。本文把这种混合延拓思想拓展成三维相位移加有限差分混合延拓法，并进一步提出了能适应速度纵、横向变化，构造任意复杂介质的三维一步法深度偏移。数值模拟试验结果表明，该方法具有移速度快、精度高的特点。
For two-dimensional steeply inclined strata, the phase-shift continuation method has the advantages of high imaging accuracy, good stability and high speed, but it is difficult to adapt to the lateral variation of speed. The finite difference algorithm in frequency and space domain is simple and stable, and can adapt to the vertical , But the imaging accuracy is low and the calculation speed is slow. However, the combination of the fast 45 ° finite difference method and the phase shift extension method can make the whole extension process not only adapt to the vertical and horizontal changes in speed but also make the steep Inclination stratum accurate homing. In this paper, the hybrid continuation idea is extended to a three-dimensional phase shift plus finite difference hybrid continuation method, and a three-dimensional one-step depth migration that can adapt to longitudinal and lateral changes in velocity and construct any complex medium is further proposed. Numerical simulation results show that this method has the characteristics of fast moving speed and high precision.