关键词: 完全匹配层, 边界条件, 频率域正演, 并行计算, 变网格

Abstract:

With the development of the computer, full-waveform inversion based on frequency-domain modeling attracts researchers’ attentions again, accordingly, PML boundary conditions for second-order acoustic wave equations and variable grid parallel computation in frequency-domain modeling are studied. PML boundary conditions is a relatively ideal absorbing boundary method and is usually used in solving the stress-velocity equations in time domain, however, for frequency acoustic wave modeling, second order displacement equation is more commonly used. We derived frequency domain second-order displacement equation PML boundary conditions from the first order acoustic wave equation PML boundary conditions and present satisfactory results of simulation examples. A single shot frequency domain modeling is implemented by solving a number of linear equations followed by an inverse Fourier transform on the records, so the frequency domain parallel computing can be performed either in different shots or in different frequencies. According to the frequency dependent character, we study the variable grid spacing computing method, using large grids in low frequencies, and small grids in high frequencies, which is one of the advantages compared to time domain modeling, and reduce the number of computation and memory consumption in the premise of ensuring the quality of simulation.

Key words: perfectly matched layer, boundary conditions, frequency-domain modeling, parallel programming, variable grid