The Lanyard and Lost Creek fields are located on the eastern flank of the Denver basin in Weld County, Colorado. Production is from the "D" sandstone interval of the Dakota Group (lower Upper Cretaceous). Combined cumulative production from both fields is in excess of 3.5 million bbl of oil and 6.7 bcf gas. Both fields are currently under secondary recovery operations.

The "D" sandstone in this area is believed to have been deposited within a channel system as part of a westward-prograding coastal plain. In places, the productive channel is no more than 1,000 ft (305 m) wide. The "D" sandstone ranges in thickness from less than 10 ft (3 m) outside of the channel to as much as 40 ft (12 m) within the channel.

An analysis of a detailed seismic grid across these fields reveals a consistent relationship between a seismic-stratigraphic anomaly and the occurrence of thick "D" sandstone. This analysis is supported by a series of seismic models based on known geologic conditions.

Depending upon localized geologic conditions, the seismic signature of a thick "D" sandstone varies across the Denver basin. However, an integrated geologic-geophysical approach can be used for the delineation of field limits as well as support for explanatory prospects or prospect leads.

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