TTI介质一阶qP波方程交错网格伪谱法正演模拟  

Staggered grid pseudo-spectral numerical simulation of first-order quasi P-wave equation for TTI media

作　　者：黄建平[1] 黄金强 李振春[1] 高国超 

机构地区：[1]中国石油大学(华东)地球科学与技术学院地球物理系,山东青岛266580

出　　处：《石油地球物理勘探》2016年第3期487-496,415,共10页Oil Geophysical Prospecting

基　　金：国家"973"课题(2014CB239006;2011CB202402);国家自然科学基金(41104069;41274124);中央高校科研业务费专项基金(R1401005A);大地测量与地球动力学国家重点实验室开放基金项目(SKLGED2015-5-2-EZ)联合资助

摘　　要：受TTI声介质强各向异性和对称轴极化倾角急剧变化的影响,传统有限差分法正演模拟易出现不稳定现象。本文基于TTI介质二阶耦合准纵(qP)波方程,推导了TTI介质一阶速度—应力方程,构建了交错网格中基于完全匹配层(PML)吸收边界条件的高阶有限差分格式;通过引入基于PML原理的一阶qP波方程伪谱法递推格式,实现了TTI介质qP波波场的稳定延拓。对二维TTI介质Wedge和BP模型的正演模拟试算结果表明:基于伪谱法递推格式实现的TTI介质正演模拟法,能较准确且稳定地模拟强各向异性及倾角变化剧烈区域的地震波场,验证了本文方法的有效性和较强适应性。Forward modeling with conventional finite difference(FD)method usually suffers from numerical instabilities due to abrupt changes of both strong anisotropy and symmetry axis tilt in titled transversely isotropic(TTI)acoustic media.We derive a set of four first-order velocity stress equations from the second-order TTI coupled equations of quasi-P wave(qP),and build a high order FD with perfectly matched layer(PML)absorbing boundary conditions in staggered grid.Furthermore,in order to improve stability about FDscheme in TTI media,we develop pseudo-spectral method,which realizes first-order qP wave equations with PML,guaranteeing a stable wave propagator.Finally,the proposed method provides stable and highly accurate TTI modeling results in 2D TTI wedge and BP model,even in models with strong anisotropy and sharp contrasts, which proves accuracy,validity and applicability of the proposed method.

关 键 词：TTI介质 准纵波 交错网格 完全匹配层 伪谱法 

分 类 号：P631[天文地球—地质矿产勘探]