复杂构造叠后逆时深度偏移

Poststack reverse-time depth migration for complex structures

中国科学院计算数学与科学工程计算研究所,北京, 100080

Institute of Computational Mathematics and Scientific Engineering Computing, Chinese Academy of Sciences, Beijing 100080

本文从三维波动方程出发,导出了用于三维叠后逆时偏移的无层间反射的波动方程,并给出了其数值算法和稳定性条件。通过对一系列二维及三维模型的偏移计算,证明了方法的正确性和有效性。与常规的深度外推偏移方法相比,它具有精度良好、计算量小、无倾角限制、避免了倏逝波能量以及能适应空间变速的一系列优点,是一种解决三维复杂构造成像的有效方法。

Starting from the 3-D wave equation, we derive a wave equation which avoids interlayer reflections and can be applied to 3-D poststack reverse-time migration. And we give its numerical algorithm and the stability condition. The migration calculations for a series of 2-D and 3-D models prove the correctncss and effectiveness of the method. Compared with the conventional depth extrapolation migration methods, the method has good preclsion, expends small computational amount, has no dip restriction, avoids the evanescent wave energy, and is adapted to both vertical and lateral velocity variations. Thus it is an effective method for imaging 3-D complex structures.