A NOVEL HIGH‐SPEED ALGORITHM FOR SUMMATIONAL TYPE SEISMIC VELOCITY ANALYSES*

Velocity analysis of reflection seismic data has increased in popularity with petroleum exploration personnel to such an extent that it now constitutes a significant tool in the routine digital processing program. One drawback to such an analysis is its computational cost, resulting from the numerous mathematical calculations required by a digital computer to extract comprehensive velocity information.

The subject algorithm affords a computational cost saving of approximately one order of magnitude over a straightforward summational type velocity analysis with little sacrifice in accuracy. The utility of the algorithm is demonstrated on some Offshore Louisiana seismic data and a comparison of the results reveals that they are almost identical with a conventional velocity analysis.

The algorithm is based on the concept that a normal‐moveout pattern of time shifts may be accurately applied over a considerable span of zero‐offset times to a CDP trace gather, rather than only at a single zero‐offset time. With each application however, the rms‐velocity associated with the moveout pattern is different. A specific relationship which associates an rms‐velocity with a zero‐offset time for the same moveout time delay pattern is approximated by numerical simulation studies on a digital computer.