Shear-wave interval velocity from P-S stacking velocities

Robert R. Stewart, Robert James Ferguson

The stacking velocity for converted waves is used to calculate a Dix interval velocity for shear waves. In synthetic examples, we find that the calculated long-wavelength shear velocity agrees well with log values. We also find that the estimated stacking velocities (and thus interval velocities) are strongly dependent on the offset range used. Small offset ranges correspond better to the assumption that stacking velocity is equal to the RMS velocity - thus allowing Dix analysis. Application to a field data set over the Blackfoot pool in S. Alberta shows reasonable agreement with an S-wave log in the area.