Relationship ofP-wave seismic attributes, azimuthal anisotropy, and commercial gas pay in 3-DP-wave multiazimuth data, Rulison Field, Piceance Basin, Colorado

• DOI: 10.1190/1.1444635
• Publication Date: 2002-10-11T19:09:34Z
• Authors: Heloise B. Lynn; David Campagna; K. Michele Simon; Wallace E. Beckham
• Keywords: Natural gas field

This case history is one of three field projects funded by the US Department Energy as part its ongoing research effort aimed to expand current levels drilling and production efficiency in naturally‐fractured tight‐gas reservoirs. The original stated goal for 3-D P-wave seismic survey was evaluate map fracture azimuth relative density throughout a gas reservoir interval. At Rulison field, this interval Cretaceous Mesaverde, approximately 2500 ft (760 m) lenticular sands, silts, shales. Three‐dimensional full‐azimuth data were acquired evaluation azimuthal anisotropy relationship commercial pay target methodology based on two restricted‐azimuth orthogonal (source‐receiver azimuth) volumes aligned with natural principal axes anisotropy, estimated from velocity analysis multiazimuth prestack gathers. Dix velocity, well amplitude variation offset (AVO) gradient, calculated both azimuths gas‐saturated Mesaverde attributes best correlated (at 21-well control set) (1) values greater than 4% ratio N60E/N30W) (the Mesaverde), (2) sum AVO gradients (N60E + N30W). an attribute sensitive presence gas, but not diagnostic amplitude. two‐azimuth mapped over area suggests spatial variations orientation maximum horizontal stress open (to flow) system.