Inter azimuth coherence attribute for fracture detection

Abstract

Fractures occur on many scales in the earth. Fractures on a sub‐seismic scale of less than tens of meters are of great interest in a reservoir context. Locating areas of greatest fracture density and determining the orientation of these fractures within a reservoir represents a significant technical challenge for geophysicists. 3‐D surface seismic data can image fractures and faults more effectively if they are sorted into common azimuth bins and analyzed separately for each azimuth bin. Based on this fact, we have developed a new algorithm to detect sub‐seismic faults and fractures by calculating coherence cubes between prestack limited azimuth seismic data. The new algorithm will calculate coherence in prestack azimuth‐sorted space, rather than poststack full azimuth space. We have applied our algorithm to a survey over a fractured reservoir in Texas, with interesting results.