A fourth‐order finite‐difference method for the acoustic wave equation on irregular grids

The design of finite-difference (FD) schemes to handle nonuniform grids is an important topic in seismic modeling. It offers the possibility of a more rational discretization once the mesh can be made locally thin to better represent structural complexities and low velocity zones, avoiding oversampling in the rest of the model. This is important in keeping the computational feasibility of the method, especially when such structures are present in realistic scale models. Examples can be found in cases where a low-velocity layer is present or the goal is to model the seismic response of a reservoir in different stages of the production (4D seismic simulation).