An adaptive free‐surface expression for three‐dimensional finite‐difference frequency‐domain modelling of elastic wave |
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| Authors: | Jian Cao Jing‐Bo Chen Meng‐Xue Dai |
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| Affiliation: | Key Laboratory of Petroleum Resources Research, Institute of Geology and Geophysics, Chinese Academy of Sciences, 100029 Beijing, China, Institutions of Earth Science, Chinese Academy of Sciences, 100029 Beijing, China, and University of Chinese Academy of Sciences, 100049 Beijing, China |
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| Abstract: | Finite‐difference frequency‐domain modelling of seismic wave propagation is attractive for its efficient solution of multisource problems, and this is crucial for full‐waveform inversion and seismic imaging, especially in the three‐dimensional seismic problem. However, implementing the free surface in the finite‐difference method is nontrivial. Based on an average medium method and the limit theorem, we present an adaptive free‐surface expression to describe the behaviour of wavefields at the free surface, and no extra work for the free‐surface boundary condition is needed. Essentially, the proposed free‐surface expression is a modification of density and constitutive relation at the free surface. In comparison with a direct difference approximate method of the free‐surface boundary condition, this adaptive free‐surface expression can produce more accurate and stable results for a broad range of Poisson's ratio. In addition, this expression has a good performance in handling the lateral variation of Poisson's ratio adaptively and without instability. |
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| Keywords: | Seismic wave modelling Free surface Frequency domain Finite difference |
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