Vector recomposition of seismic 3-d converted-wave data

Abstract

The instant invention pertains generally to a method of seismic processing of multi-component converted wave 2-D and 3-D seismic data, wherein the seismic traces in each CCP gather may have been acquired at a variety of different source-receiver azimuths. According to one aspect of the instant invention there is provided a method of using recorded multi-component seismic data to determine an estimate of the orientation of the two principle coordinate axes of a subsurface medium, with this determination potentially being made in each seismic survey bin, and for each depth. Given this estimate, the seismic data may then be transformed via rotation into the coordinate system so defined, and thereafter processed using conventional algorithms (e.g., to produce velocity functions and images). Another embodiment of the instant invention uses a given principle coordinate axis orientation—which might have been obtained via the previous embodiment—to calculate a “best” data reduction of the traces in the CCP. In either case, the present invention additionally solves the problem of deducing the principal times series and provides a means of combining multi-azimuth multi-component CCP gathers for further conventional scalar processing. Those skilled in the art will appreciate that the methods disclosed below would be especially useful in 3-D surveys and in 2-D crooked line surveys.