Weighted nearly-analytical discrete (WNAD) method is a new numerical technology developed in recent years, which can effectively suppress the numerical dispersion when a coarse grid is used. However, using a large spatial step is not always suitable for any seismic exploration cases. In order to meet the actual requirement of seismic wave-field simulations, the authors suggest a non-uniform grid algorithm based on the WNAD method to solve the wave equations in this paper. This algorithm uses a fine spatial grid in special computational domains such as the low-velocity areas and complicated media, and adopts a coarse spatial grid in the rest computational domains. Based on the characteristics of the WNAD method, this non-uniform grid algorithm uses a new interpolation formula to connect the fine grids and the coarse grids in the transition zone, thus obtains higher interpolation accuracy through using fewer grids. Numerical results show that the non-uniform grid algorithm can suppress effectively the numerical dispersion, and reduce the storage spaces and computational costs, resulting in further increasing the computational efficiency of seismic wave-field simulations.
