The seismic characterization of the Niobrara presented here is based on recently acquired wide-azimuth 3D seismic data in Weld County, N.E Colorado (Figure 1), and publically available well data for calibration within the area. The presentation starts with the location and geologic setting of the Niobrara and its vertical reference to the seismic response (Figure 2). An association is made using geometric attributes relating the complex subtle faulting to the Laramide Orogeny, which occurred in a series of pulses with intervening quiescent phases, possibly influencing hydrocarbon production. This sets the local structural framework for using fracture anisotropy and related rock properties for locating possible areas of significant interest.
The Niobrara Formation lies in a thermally mature fairway which today is the Denver-Julesburg Basin. These sediments were deposited in an ancient Cretaceous seaway (Western Interior Seaway) running in a north-south direction through the mid-western United States, with ends open to the ocean. The Niobrara is carbonate rich on the east side, where the study area is located producing oil, and clay rich on the west side of the Basin. The Smoky Hill Chalk Member is 300–400 ft thick and composed of three key limestones (chalk) benches A, B and C which are each approximately 30–40 ft. thick (Figure 2). They are named from their resistive nature as seen along cliff exposures, and are intercalated with organic rich marls, the source rock.