快速精确的二维频率空间域弹性波数值模拟

二维频率空间域的数值模拟方法具有以下的优势:多炮模拟时,计算成本比时间域方法低;无累计误差;在地震反演中处理多震源模拟时,只需要有限的几个频率就可以得到好的反演结果.差分离散化形成的稀疏系数矩阵,需要求解一个巨大规模的线性方程组,最大瓶颈是需要海量的计算机内存,导致计算量庞大.本文在前人研究的基础上,采用嵌套剖分网格排序法,极大限度减少对计算机内存的需求,从而减少了计算量.针对弹性波数值模拟的特征,提出二维频率空间域弹性波多炮模拟的快速计算流程.数值模拟试验证明使用嵌套剖分排序法的弹性波多炮数值模拟比压缩存储法具有节省存储量、计算效率高等优势,为后续的二维频率空间域弹性波全波形反演奠定了很好的基础.

2-D rapid accurate elastic wave numerical simulation method in frequency space domain

There are many advantages of the two dimensional numerical simulation on seismic waves in frequency space domain:the calculating cost of a large number of sources in frequency space domain is much lower than that of time domain methods.Without accumulative errors,it is very useful in dealing with the multiple source simulation in seismic inversion,it can get good inversion results only with several frequencies.Once the frequency domain equations are discretized to form matrix equation.The coefficient matrix is a very huge and sparse band matrix equation.We need solve a large number of linear equations,the biggest bottleneck of frequency domain simulation method is the huge demand for computer’s memory and computing amount.We adopt the nested-dissection method which can decrease the requiring of computer capacity greatly and decrease the computing cost based on the former’s paper.For multi-shot forward modeling’s charactering,This paper presents a fast computational procedure of numerical simulation elastic wave in frequency space domain.Numerical results demonstrate that nested-dissection has many advantages comparing to compressed storage format,such as saving a huge storage and computing time as well as high computing efficiency,which provides a good base for the 2-D elastic wave full waveform inversion.