Applying interferometry to converted wave statics
David C. Henley, P. F. Daley
In recent years, a wide variety of seismic processing techniques has appeared in the geophysical literature under the general heading of `seismic interferometry'. Most of the algorithms are for producing images from sets of seismic traces recorded using either well defined sources or random background microseisms, and all are characterized by the procedure of cross-correlating raw traces and, usually, summing the correlations over spatial apertures. In fact, it's the cross-correlation that most specifically distinguishes interferometry from other seismic imaging techniques; and its purpose is to zero some common part of the phase difference between the input traces. Our `statics deconvolution' method embodies the interferometric principle to remove time/phase differences in seismic traces recorded with common sources, receivers, or near-surface raypaths. Here, we attempt to use interferometry to correct converted wave seismic data for near-surface effects along the shear wave portions of the seismic propagation paths. Preliminary results show that we can improve the coherency of stacked converted wave events, but that preserving geologic structure is an unsolved problem. Likewise, we find some encouragement for the use of methods not involving `pilot traces' but these methods need to be further developed.