相比于VTI介质qP波数值模拟方法,考虑倾角因素的TTI介质qP波数值模拟方法能够更加准确地描述各向异性介质中波场的传播特征. 常规的声学近似方法往往会造成TTI介质中倾角急剧变化的区域出现数值不稳定,笔者首先引入一个各向异性控制参数,推导了稳定形式的TTI介质二阶qP波方程,保证qP波场的稳定传播;其次,通过引入波场的伪速度分量,推导了其等价的一阶应力—速度形式及相应的PML边界条件,并应用优化的旋转交错网格有限差分( RSGFD)方法实现了精确的数值模拟. 数值结果表明:TTI介质一阶qP波方程能够稳定、有效地模拟qP波的运动学特征,利用优化的RSGFD方法可以得到精确的合成地震记录,同时可以相对地提高计算效率.%Compared with VTI qP-wave modeling,TTI qP-wave numerical simulation method which considers dip angle factor could be more accurate in describing the characteristics of wave-field propagation in real anisotropic media.Because of the rapid change of dip an-gle in TTI media,using the conventional acoustic approximated method may cause numerical instability.In this paper,the authors first derived the stable TTI second-order qP-wave equations by introducing an anisotropic control parameter to ensure the stability of qP-wave propagation.Then,the equivalent first-order stress-velocity forms were deduced through introducing the pseudo-velocity components of the wave-fields,and the corresponding PML boundary condition was given.Finally,the authors implemented accurate numerical simula-tion using the optimal rotated stagger-grid finite-difference ( RSGFD) method. Numerical results demonstrate that TTI first-order qP-wave equations can describe the kinematics features of qP-wave effectively and stably,and the application of optimal RSGFD method can acquire accurate synthetic seismic recordings and enhance computational efficiency relatively.
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