频率域单程方程三维叠前正演中的波场替换

利用定位原理进行三维叠前正演，仅靠单程声波方程的延拓即可形成地质条件下的正深记录，运算效率高无多次反射出现，但速度模型中对过大或过小的速度常使波场在延拓时有频率和波数成分的损失，这种损失引起波场畸变并严重影响正演记录的质量，本文采用波场替换技术，在每次延拓时用零相位子波表成一个同时保辄原波场的动力学特征与空间位置信息的新波场，然后用新波场取代原畸变波场并参与正演记录合成，在频率域单程方程三维叠前正演中特别适合做波场替换，因为，震源脉冲与接收响应（均可视为点脉冲）的延拓波场在形态上相似，而且在延拓波场中道记录之振幅包络只有一个极值点，理论试算结果表明，采用波场替换技术后最终正演记录质量比替换前有了很大改善。

Wavefield replacement in 3D prestack forward modeling based on one way acoustic wave equation of frequency domain

Based on the seismic positioning principle we can do 3D prestack forward modeling by one way acoustic wave equation in complex geological conditions.This method has very high caculating efficiency and hasn't multi reflections in the seismic records.But unsuitable velocity in model usually result in frequency and wave number's lossing of wave field that cause wave field's aberration and reduce quality of seismic forward records.This paper proposes wave field replacement technology which uses new wave field formed by zero phase wavelet to replace old aberrant wave field and keep old one's dynamical and spacial characteristic at the same time.It is very suitable to use this technology in 3D prestack forward modeling because the wave field of focus and receiver's response are similar in shape and every trace's amplitude envelope in wave field only has one extreme value.The simulation shows that the record's quality is improved when using wave field replacement technology.