High-precision spatial and temporal arbitrary multiple variable grid finite difference forward modeling method

The invention provides a high-precision spatial and temporal arbitrary multiple variable grid finite difference forward modeling method, which comprises the steps of: step 1, establishing a forward modeling speed model of an underground medium; step 2, subjecting the forward modeling speed model to two-dimensional grid discretization, and subjecting an acoustic wave field in the forward modeling speed model to two-dimensional grid discretization, wherein the acoustic wave field is located on grid nodes; step 3, subjecting a perfectly matched layer boundary condition to grid discretization; and step 4, conducting time-domain finite difference forward modeling simulation through an acoustic wave equation, wherein time sampling step lengths are variable step lengths at grids of different sizes. The high-precision spatial and temporal arbitrary multiple variable grid finite difference forward modeling method can effectively suppress forward modeling frequency dispersion, significantly increases signal-to-noise ratio, and greatly improves precision and efficiency of forward modeling simulation.