CONCLUSIONS

There are several possible ways in which well-logs can be correlated. The choice of the matching attribute must be controlled by the geologic feature that one is trying to resolve. A smoothed version of the sonic log is most appropriate for lithologic matching, and can therefore be used as a constraint to a tomographic inversion. In this case, remains the question of whether to match amplitudes or shapes, a choice that can be particularly critical when a strong lateral velocity variation is present. Moreover, if the goal is to find the correlation between chronostratigraphic units that are resolved in a surface seismic section, the usual synthetic seismogram may not be the optimal choice. Extensive lateral continuity in a seismic section is related to the specific patterns in the impedance transitions, rather than to the transition values. As a result, the output of a filter that measures the local variability of the sonic log provides a better chronostratigraphic correlation between wells covering an extensive area than conventional synthetic seismograms.