Observation of Shear-Wave Splitting and Dispersion in Walkaround VSP Data from Saudi Arabia

Shear waves propagating through an anisotropic medium split into two approximately orthogonal phases with different velocities. For a single set of fractures, the faster shear wave is polarized along the fracture planes, while the slower shear wave is polarized in a direction orthogonal to the fracture planes. For multiple sets of fractures, the faster shear is not polarized along one specific fracture plane. In this paper, shear-wave splitting analysis for walkaround VSP data was applied for the characterization of multiple sets fractures. Dispersion of the downgoing S- and reflected P-waves was also investigated as a way to discriminate between open and closed fractures.