Close full-size image and return to story.
Figure 2 – Relationship between slow-S velocity (S2) and fracture density (FD). As fracture
density increases, S2 velocity decreases. In contrast, fast-S velocity S1 and P-wave velocity
VP do not change, or change by only minor amounts across blocks A through E. In isotropic
blocks A and E, there is no S-wave splitting and only one S-wave velocity VS. In all blocks (A
through E), fast-S velocity = VS, the velocity in the non-fractured rock. Mineralogy, porosity and
pore fluid do not change across the profile. The only Earth properties that vary from block to
block are fracture density and orientation.