VSP弹性波方程正演模拟与波场分析

The equation forward modeling and wave field analysis of VSP elastic wave

本文采用的VSP弹性波方程交错网格高阶差分法网格频散小、边界吸收精度高。不同井源距VSP正演结果表明,随着井源距增加,波场干涉对直达波影响加重、各类波场非线性特征趋于明显、能量分布特征变化增大,特别是上行反射P波与上行转换SV波视速度差异变小。这些结果在三维VSP处理中都要有足够的重视。

The staggered-mesh higher difference of VSP elastic wave equation has a less mesh dispersion and higher boundary absorption precision. The results forwarded from different offset VSP demonstrated that the wave field interference have stronger impact on direct waves, non-liner features of all kinds of wave field appears more obvious and the feature of energy distribution vary greater along with the offset distance become longer, especially the apparent velocity difference of upgoing reflection P wave and upgoing converted SV wave become less. All these should be paid more attention in 3D VSP data processing.