Seismic wavefield modeling based on time-domain symplectic and Fourier finite-difference method
Fang Gang1,2, Ba Jing3, Liu Xin-Xin1,2, Zhu Kun4, and Liu Guo-Chang5
1. The Key Laboratory of Gas Hydrate, Ministry of Land and Resources, Qingdao Institute of Marine Geology, Qingdao 266071, China.
2. Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China.
3. School of Earth Sciences and Engineering, Hohai University, Nanjing 211100, China.
4. School of Geosciences, China University of Petroleum (East China), Qingdao 266580, China.
5. State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum-Beijing, Beijing 102249, China.
Abstract：
Seismic wavefield modeling is important for improving seismic data processing and interpretation. Calculations of wavefield propagation are sometimes not stable when forward modeling of seismic wave uses large time steps for long times. Based on the Hamiltonian expression of the acoustic wave equation, we propose a structure-preserving method for seismic wavefield modeling by applying the symplectic finite-difference method on time grids and the Fourier finite-difference method on space grids to solve the acoustic wave equation. The proposed method is called the symplectic Fourier finite-difference (symplectic FFD) method, and offers high computational accuracy and improves the computational stability. Using acoustic approximation, we extend the method to anisotropic media. We discuss the calculations in the symplectic FFD method for seismic wavefield modeling of isotropic and anisotropic media, and use the BP salt model and BP TTI model to test the proposed method. The numerical examples suggest that the proposed method can be used in seismic modeling of strongly variable velocities, offering high computational accuracy and low numerical dispersion. The symplectic FFD method overcomes the residual qSV wave of seismic modeling in anisotropic media and maintains the stability of the wavefield propagation for large time steps.
. Seismic wavefield modeling based on time-domain symplectic and Fourier finite-difference method[J]. APPLIED GEOPHYSICS, 2017, 14(2): 258-269.
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2017, Vol. 14 
