完全匹配层吸收边界条件应用研究

Application investigation of perfectly matched layer absorbing boundary condition

在地震波正演和波动方程偏移的数值计算中,人工边界的引入限制了实际计算区域的大小,边界处反射波的能量严重影响数值计算结果.文中研究了完全匹配层(PML)吸收边界条件在地震波正演及逆时偏移中的有效应用,将PML边界条件的衰减因子引入到声波方程中,利用有限差分的数值方法求解声波方程,在保证差分近似稳定性的情况下,也使边界处的人工反射得到了最小化的处理.数值结果表明,文中所述的完全匹配层方法对地震波的吸收能力不受入射角度的限制,在地震波传播的数值模拟以及叠前逆时偏移算法测试中,均能有效地吸收地震波,是一种高效的边界吸收算法.

In practical calculations, typically in seismic data forward modeling and wave-equation prestack migration, it is often essential to introduce artificial boundaries to limit the area of computation, but the artificial boundaries can reflect the wave energy, these energy is serious for modeled shot record and migration seismic dataset. The application and effect of perfectly matched layer （PML） in seismic data modeling and reverse time migration is demonstrated in this paper, the attenuation factor of PML is introduced in acoustic equation, and solve the equation used the finite difference approach. These boundary conditions not only guarantee stable difference approximation, but also minimize the artificial reflections that occur at the boundaries. Numerical results demonstrate that the perfectly matched layer （PML） boundary condition used in the paper can effectively absorb the seismic wave in boundaries, have no limits of wave incidence angle, and it is effective boundary absorbing algorithm.