Interferometric Rayparameter Estimation and Applications

Modern seismic surveys accumulate large amounts of data due to the increased channel and shot counts (see Rached et al., 2006). Therefore we need to move away from the manual estimation of the first breaks, needed for the production of refraction based static corrections, and instead use more automatic methods. The novel technique described here is based on the theory of seismic interferometry to the estimation of rayparameter values as function of source and receiver offset. Seismic interferometry is the process of creating secondary seismic traces (interferograms) from pairs of genuine seismograms by cross-correlation (or spectral division). One major benefit of dealing with interferograms is that of estimating delay times by picking maxima of interferograms as opposed to picking first-break travel times from the actual seismograms. One application of the estimated rayparameter is to enhance automatic first break picking. The rayparameter is estimated in the region of the first breaks and is subsequently used in the stacking of adjacent traces. The stacked traces, with an improved signal-to-noise ratio, are analyzed in place of the original traces to provide better estimates of the first break times.