Abstract

Hells Hole Field is located on the west side of the Douglas Creek Arch on the northwest plunge of the West Douglas Creek Anticline on the eastern edge of the Uinta Basin, some 15 miles southwest of Rangely Field (Fig. 1). The Dakota Sandstone Formation is subdivided informally into upper (A and B), middle (C) and lower (D) Dakota sandstones. Production, primarily from the upper Dakota, is stratigraphic in nature with no production, as yet, confined to areas of structural closures. Depositional facies and lithofacies variations and porosity and permeability changes within the sands provide the trapping mechanism.

The upper Dakota sands were deposited as part of a northwest/southeast trending wave dominated delta complex. The Dakota A sandstones represent a local progradation of a depositional system that otherwise transgressed southwestward across Colorado. Sand deposition was influenced by a local still stand of the shoreline and a local topographic high controlled by syndepositional faulting.

Structure mapped on the top of the upper Dakota A sandstone interval exhibits the trap door structure described by Stone (1969). Though this provides little closure it does define this portion of the West Douglas Creek Anticline which forms the basis for the stratigraphic trapping observed. Isopach mapping reveals thinning in the Cretaceous Dakota to Mississippian Leadville interval at Hells Hole indicating the feature had expression during the Paleozoic. This may allow for significant gas potential in the deeper rocks.