论文部分内容阅读
由于各向异性广泛存在于地下岩石中,随着勘探精度的不断提高,对地下介质的各向同性假设越来越不能够满足于现状,因此对各向异性介质的数值模拟显得更为重要。本文推导了各向异性介质的弹性波动方程,总结了震源类型,通过PML方法处理了人工边界问题,通过快照分析验证了数值频散、稳定性条件。研究结果表明:(1)PML完全匹配层,可较好地解决人工边界问题;(2)减小空间采样间隔压制数值频散比减小时间采样间隔效果要好得多,盲目减小时间采样间隔会大大降低数值模拟的运算效率;(3)各向异性介质中弹性波场中除含有准纵波外,还含有速度较慢的准横波;(4)准纵波波前能量要比由各向异性引起的准横波能量强,准纵波和准横波的波前随着各向异性介质参数的变化而变化。
As anisotropy exists widely in underground rocks, as the accuracy of exploration increases, the isotropic assumption of underground media can not be satisfied with the status quo. Therefore, the numerical simulation of anisotropic media is even more important. In this paper, the elastic wave equation of anisotropic medium is deduced, the type of source is summarized, the artificial boundary problem is solved by PML method, and the numerical dispersion and stability conditions are verified by snapshot analysis. The results show that: (1) PML perfect matching layer can solve the artificial boundary problem well; (2) reduce the spatial sampling interval suppression numerical dispersion is much better than reducing the time sampling interval, blindly reduce the time sampling interval Will greatly reduce the computational efficiency of numerical simulation; (3) In anisotropic media, the elastic wave field contains quasi-longitudinal waves in addition to quasi-longitudinal waves, and quasi-transverse waves with slower speeds; (4) The quasi-transverse wave energy is strong, and the wave front of quasi-longitudinal wave and quasi-transverse wave changes with the change of anisotropic media parameters.