Patent ID: 6289285
Filing Date: 2001-09-11
Classification: G01V

Abstract:
A method of processing seismic data for a velocity analysis, wherein said data corresponds to a vertical seismic record section, and wherein trace data in said record section includes multiple offsets, and further includes traces exhibiting a polarity reversal with offset in at least a portion of said record section, and wherein said traces exhibiting polarity reversal are presented as contours of coherency in a graphic display of said velocity analysis, said method comprising:a) applying normal moveout (NMO) to all traces in said seismic record section;b) defining a plurality of subgroups, wherein each subgroup comprises a plurality of adjacent traces in said record section, and further defining a length of a time for a comparison window;c) determining a measure of multi-trace coherency for each of said plurality of subgroups using a sliding time window technique and an extended cross-correlation algorithm for determining said measure of multi-trace coherency, and wherein said measure of multi-trace coherency includes values which are representative of said traces exhibiting polarity reversal with offset; andd) graphically displaying said velocity analysis in a time-velocity domain, and including contours of said multi-trace coherency based on said measure of multi-trace coherency for each of said plurality of subgroups determined in step c).