Processing wavefield data incorporating large timesteps and upscaled medium properties

摘要

The present invention relates to processing data representing a wavefield propagating through a medium. A desired timestep and a desired spatial step are defined, based on one or more properties of a region of the medium and of the wavefield therein, for a discrete operator 901. Discrete seed operators having an initial timestep and an initial spatial step less than the desired timestep and the desired spatial step are then defined 902, and these seed operators are compounded 903 to obtain an operator having a greater timestep and upscaled 904 to obtain an operator having a greater spatial step. The compounding and upscaling are repeated until an operator having the desired timestep and the desired spatial step is obtained. The operator having the desired timestep and the desired spatial step is applied to the data representing the wavefield propagating through a medium to propagate the data backwards in time to recreate the wavefield at earlier times 906. By increasing the timestep, the efficiency of the method is improved as fewer steps are required to model backwards through a known time period.