Inversion of donor vertical time shifts to update a near-surface depth/velocity model

Abstract

The near-surface model for static corrections requires a consistent regional depth/velocity model, while incorporating the fidelity of additional static solutions. We addressed the challenge of tying new seismic acquisition to a depth/velocity model, in which there are static corrections derived independently for each seismic data. The generalized method is a four-step procedure that starts with the grafting of the additional shifts to the recipient static model. The time shifts were then adjusted to constrain the long wavelength at defined locations. The next procedure was to split the time shifts into high- and low-frequency components. The final procedure inverted the high frequency into the shallowest layers and the long wavelength to the velocity from base of model to datum. The result was an updated regional depth/velocity model into which new 2D depth/velocity models could be tied. The generalized solution would work with any additional near-surface static corrections, which could include, and not be limited to, those built from surface waves, remote sensing, and joint inversion with nonseismic data. The inversion of the additional time shifts was primarily intended to provide a solution to their tie and any image improvement is serendipitous. We progressively learned lessons from a simple inversion and achieved the generalized solution.