含裂隙介质中横波分裂现象的数值模拟

Numerical Modeling and Study of the Shear Wave-splitting in Fracture Media

波动方程高阶差分法具有精度高、数值频散小的优点 .使用这种高阶差分解法 ,对裂隙介质中的弹性波的传播进行了模拟 ,对其中的横波分裂现象进行了分析研究 .结果发现 ,在裂隙介质中 ,横波分裂后快横波与慢横波的能量分布与裂隙和测线的夹角有关 ;慢横波的能量衰减快 ;快、慢横波遇到反射界面时会产生各自的反射波、透射波和转换波 ,使记录复杂化 .模拟结果对裂隙发育地区的地震资料的采集、处理和解释具有指导意义 .

The high-order difference method of wave equation has the advantages of high accuracy and small numerical dispersion. In this article the propagation of elastic wave in fracture media is simulated with this method and the results are analyzed. It is revealed that in fracture media the shear-wave splits into two components, a fast one and a slow one. Their energy changes with the angle between the fracture strike and the in-line by a simple relationship of cosine function. The slow shear-wave attenuates faster than the fast one. When they meet with a interface, both split parts of the s-wave may produce reflection, transmission and conversion, which complicates the record. These simulation results contribute to the seismic data collecting, processing and interpretation in the region with fracture distribution.