By Scott Taylor, Jeremy King, Ben Schaeffer, Todd Hibbitts, Lucas McGreaham and Khaled Ghuneim HOUSTON-Perforation shots typically are used in conjunction with velocity information derived from sonic well logs to build a velocity model suitable for mapping microseismic events. These models typically assume lateral homogeneity, which may not honor the geologic properties of the medium being modeled. Despite considerable improvements in seismic data quality and imaging algorithms, velocities and earth models remain the key challenges for high-confidence (i.e., low-risk) depth prediction. The key question is whether more value can be extracted from microseismic surveys across a broad spectrum of wells by simultaneously solving for a geologically meaningful 3-D anisotropic velocity model from both perforation shots and certain microseismic events themselves. More specifically, can elastic rock properties be extracted from microseismic data and be projected onto a high-resolution 3-D reservoir grid to guide reservoir development? PART TWO FEBRUARY 2017 43