•Early estimation of principal S-wave orientation is critical for processing.
•Alford rotation analysis is a valuable tool to quantify the time variant S-wave birefringence.
•More intense azimuthal anisotropy on the crest and flanks of the Pinedale anticline suggest potential fracture sweet spots.
•Fast S-wave direction agrees with the strike of near vertical fractures on the FMI log, and appears to be sensitive to local horizontal stresses.
Conclusions