High-Resolution Velocity Analysis by Sign Time-Shift Semblance

Velocity analysis is one of the important steps in seismic data processing, and accurate velocity parameters are a necessary condition for achieving good results in subsequent seismic exploration processing. The conventional velocity analysis based on semblance function is not applicable to gather with polarity reversal, and the resolution of the method is poor. Improving the resolution of the velocity spectrum is beneficial for picking up the true normal moveout (NMO) correction velocity. On the basis of conventional semblance function, we introduce a sign function to solve the polarity reversal problem, and then introduce a time-shift function to improve the resolution of the velocity spectrum. The application of synthetic and field data validated the effectiveness of the proposed technique. The comparison with previous methods shows that the proposed technique is not only applicable to the gather with polarity reversal, but also can obtain high-precision and high-resolution velocity spectra.