Inversion of seismic refraction data in planar dipping structure

A new method is presented for the direct inversion of seismic refraction data in dipping planar structure. Three recording geometries, each consisting of two common-shot profiles, are considered: reversed, split, and roll-along profiles. Inversion is achieved via slant stacking the common-shot wavefield to obtain a delay time—slowness (tau—p) wavefield. The tau—p curves from two shotpoints describing the critical raypath of refracted and post-critically reflected arrivals are automatically picked using coherency measurements and the two curves are jointly used to calculate velocity and dip of isovelocity lines iteratively, thereby obtaining the final two-dimensional velocity model.

This procedure has been successfully applied to synthetic seismograms calculated for a dipping structure and to field data from central California. The results indicate that direct inversion of closely-spaced refraction/wide-aperture reflection data can practically be achieved in laterally inhomogeneous structures.