基于“方程解耦”算法的各向异性介质纵横波分离方法

各向异性介质纵横波耦合的特性，使得纵波信息的获取对于各向异性非常规储层地震数据采集和处理具有重要意义.常规方法主要包括基于散度旋度场的Helmholtz分解和基于频散关系的声波近似等两大类，但这两类方法都改变了纵波波场的振幅和相位信息，并进一步影响正演数值模拟和纵波偏移成像的最终结果.本文基于方程解耦的思想，通过将弹性刚度系数分量中的纵横波耦合项近似为纵波模量和横波模量的线性函数，推导得到单独的纵波和横波方程，从而实现各向异性介质的纵横波波场分离.与常规方法相比，"方程解耦"方法得到的纵波波场的振幅和相位信息都更为准确，且波场信息也更为完整，能够为各向异性介质的纵波数据处理提供重要的保障.

Elastic wave-mode separation for anisotropic media based on equation-decoupling method

Due to the coupling characteristics of P-wave and S-wave in anisotropic media, the acquisition of P-wave information is of great significance for seismic data acquisition and processing of anisotropic unconventional reservoirs. Conventional methods are mainly divided into two categories: Helmholtz decomposition based on divergence curl field and acoustic approximation based on dispersion relation. However, both of these methods change the amplitude and phase information of P-wave field, and further affect the final results of forward numerical simulation and P-wave migration imaging. Based on the equation-decoupling method, the coupling terms of P-wave and S-wave in the component of elastic stiffness coefficient are approximated to linear functions of P- and S-wave modulus, and the separate P-wave and S-wave equations are derived, so as to realize the separation of P-wave and S-wave fields in anisotropic media. Compared with the conventional method, the amplitude and phase information of P-wave field obtained by the "equation-decoupling" algorithm is more accurate, and the wave field information is more complete, which can provide an important guarantee for P-wave data processing in anisotropic media.