【摘要】 本文根据具有垂直对称轴的横向各向同性(VTI)介质中的一阶准P波方程,构造了该方程在交错网格中求解的高阶有限差分格式,给出了其稳定性条件;重点研究了适用于该方程的完全匹配层(PML)吸收边界条件,在此基础上实现了VTI介质中一阶准P波方程的正演模拟,得到了高精度的波场快照和合成记录,并采用叠前逆时深度偏移算法对复杂模型的合成记录进行偏移成像,得到了较好的成像效果。数值算例表明:准P波方程正演模拟能克服常规弹性波方程正演模拟的某些缺陷,便于研究各向异性介质中纵波的传播机理;叠前逆时深度偏移算法能够对复杂模型准确成像;通过对比分析各向同性与各向异性Marmousi模型的合成记录以及两种偏移算法的成像结果,显示各向异性参数对波场特征(旅行时和振幅)会产生明显影响,在地震资料处理、反演和解释中不可忽略。更多还原

【Abstract】 Based on the first-order Quasi-P wave equation in VTI medium,the high-order finite difference scheme of the equation which was solved in the staggered grid was constructed in this paper,the stability condition of the equation was also given,the Perfectly Matched Layer(PML)absorbing boundary conditions which fit the equation were thoroughly studied in this paper,based on the studies above the forward modeling was realized for the first-order Quasi-P wave equation in VTI medium,high precision wavefield snapshot and synthetic record were obtained,the pre-stack reverse-time depth migration algorithm was used to conduct migration imaging for the complicated model,then good imaging results were achieved.The numerical experiments show that the Quasi-P wave equation forward modeling can overcome some of the defects of the conventional wave equation modeling,it also can facilitate the research on wave propagation mechanism in the anisotropic medium.The pre-stack reverse-time depth migration algorithm could accurately image the complex models;by comparing and analyzing the synthetic records and imaging results of the two migration algorithms for the isotropic and anisotropic Marmousi model,it can be indicated that the anisotropic parameters will have significant influence on the wave field characteristics(travel time and amplitude),which can not be ignored in the seismic data processing,inversion and interpretation.更多还原