VELOCITY-DEPTH AMBIGUITY OF REFLECTION TRAVEL-TIMES

The conversion of time horizons to depth is fundamental to exploration geophysics. The interval velocity used in the conversion is often estimated from the stacking velocity. It is shown that violent swings in the stacking velocity are a symptom of a long-wavelength ambiguity between the burial depth to an interface and interval velocity. A practical inverse filter than corrects for these distortions produces an interval velocity that is almost totally lacking in low-frequency components, giving a very distorted picture of the interval velocity. A two-channel Wiener filter was employed, but results suggest that the velocity-depth ambiguity may continue to plague exploration seismologists for some time to come. -from Author