Fourier finite-difference forward modeling in visco-acoustic media

Earth absorption effect mainly resulted from the viscosity of earth media itself, which can affect all frequency components of wavefield, especially for high-frequency elements, leading vertical resolution of seismic data to reduce. The paper popularizes the Fourier finite-difference method in full-elastic media to the forward field in visco-acoustic media, which is one-way wave method in frequency domain and has superiority in computational efficiency if comparison with two-way wave method, and is easier simulation of attenuation and dispersion effects than in time domain. The paper carried out forward modeling for Marmousi model in visco-acoustic media, and the numeric case showed: 1, the consistency of feature of amplitude and phase between the visco-acoustic media and full-elastic media is only in the part of short travel time and near shot points at the same time, showing absorption effect by viscosity has large influence on waveform, frequency band and amplitude of seismic wave; 2, along with increasing of the travel distance (time), the high-frequency components in wavefield show clear attenuation, the waveform is gradually widening and the energy is gradually weakening. The method presented in the paper is suitable for forward simulation in large velocity-changed media in space, and has higher computational efficiency, laying the foundation for deep study of earth absorption effect and further improvement of seismic resolution.