A METHOD OF CONTINUOUS VELOCITY ANALYSIS

Abstract

This continuous velocity analysis technique is a development of previous automated computer methods for extracting velocity information from seismic reflection data. Every trace of the multi-fold coverage data is used to measure the time, amplitude, moveout and dip of each coherent reflection event on the seismic records, by means of moveout scan and dip scan techniques. Using these four parameters, reflection events are tracked along the line, finally producing a computer file on each reflection event, listing its time, amplitude and moveout at each depth point along its extent. The signal to noise ratio increase given by the moveout and dip scan processes is greater than that achieved on the final section, allowing the computer to pick events close to the limit of visibility on the final section. The velocity information obtained can be displayed in various ways, for use in estimating velocity functions for data processes such as moveout correction, time migration, and depth conversion, and for use by the interpreter in such things as the measurement of interval velocities and the estimation of sand-shale ratios.