Seismic Characterization of Fractured Tight Gas Reservoirs, Piceance Basin, Colorado

The Piceance basin has large gas reserves stored in a thick section of tight clastic rocks. Fractures can significantly enhance production and the reliable pre-drill prediction of fracture anomalies is the key to economic success. An extensive test combining logging, core measurements, numerical modeling, borehole seismic and surface seismic data has been collected in the northern Piceance basin to determine the seismic characterization of fractures. Preliminary results to date include: • Fractures occur in sand intervals • Seismic anisotropy (P- and S-wave) has a positive correlation to fracture occurrence • Anomalies exist when anisotropic P-wave modeling is compared to isotropic results. This phenomenon may be enhanced for PS-converted waves. Remaining work will examine whether these observations may be observed on surface measurements.