Abstract: Defining an appropriate discrete grid is a crucial part of frequency-domain modelling and imaging. The results of the illumination analysis, modelling and migration were applied to investigate the relationship among time step, trace interval and spatial grid interval for the Padé generalized screen propagator. Numerical tests indicate that the stability condition must be satisfied when defining grid discritization strategies, or the frequency-domain migration result could be mistakenly interpreted due to the existence of unexpected coherent noise. Besides, when migrating the insufficient spatial-sparse-sampling data, the spatial grid doesnt have to be too fine. And the regular interpolations among traces can hardly improve the migration result. Therefore its more reasonable to inject zero-value traces on grid points between adjacent receivers than using interpolation. This study provides an important reference for efficiently defining discrete grids for other frequency-domain methods.

Key words: frequency-domain, wave propagation, modelling, migration, noise