Direct Statics Estimation from Ground Roll Data - The Role of Higher Modes

Statics correction can be computed by inverting the dispersion curves of surface waves. Here, we directly estimate the statics correction from the dispersion curves of surface waves, without the need for inverting the data. This can be achieved by finding the relationship between the time average S-wave velocity at different depths and the surface-wave phase velocity at different wavelengths. The same approach is found for the estimation of weighted average P-wave velocity, by exploiting the sensitivity of the wavelength/depth relationship to Poisson’s ratio. Prior information of the S-wave velocity profile corresponding to only one of the dispersion curves in the area is required. We show on a synthetic dataset the possibility of extending this method to higher modes of surface waves. The fundamental mode showed a greater sensitivity to Poisson’s ratio compared to the first higher mode. We show the successful application of this method on an oil and gas dataset in a sand dune area. By having only the ground roll in the data and a single profile of VS, we directly estimate the P- and S-wave statics correction. We also show a comparable analysis between fundamental and first higher modes of ground roll for the estimation of statics.