Structural Analysis of the Piceance Basin, Northwestern Colorado

Renaud Bouroullec and Paul Weimer

The Piceance Basin in northwestern Colorado is an active petroleum province with 38 fields, including 18 with conventional traps, and 21 as part of the basin centered gas accumulation, the latter totaling gas production of 1.2 bcf/day. This study defines the regional structure of the Piceance Basin through correlation of key surfaces from 700 km of 2-D seismic data, and construction of time-structure and isochron maps. The main structural events affecting the basin since the Cambrian include the Ancestral Rocky Mountain, Sevier, and Laramide Orogenies. The Laurasia/Gondwana collision during Pennsylvanian generated a series of uplifted zones including the Uncompahgre and Front Range uplifts, and associated basins, included the Paradox, Raton and Eagle basins. This tectonic phase corresponds to the Ancestral Rockies orogen and was active from Pennsylvanian to Permian. The Paleozoic strata and Basement are imaged in the 2-D dataset, and both normal and reverse basement faults are observed. Some normal basement faults were reactivated during the Pennsylvanian as reverse faults, such as underneath the Divide Creek Anticline. Erosion at the base Jurassic is observed locally with Pennsylvanian to Triassic strata missing. Some evidence of Late Cretaceous shortening is observed in the Piceance Basin and attributed to the Sevier Orogeny. These structures include the Axial Arch with minor Laramide-age reactivation and reactivated Pennsylvanian basement faults showing deformation of the lower Upper Cretaceous Mancos Shale including growth geometries with stratal onlap onto growth structures. The Laramide Orogeny was active from latest Cretaceous to Eocene (70-40 Ma), with successive structural growth at Douglas Creek arch, Axial arch, White River uplift, and Carbondale uplift. This last phase of deformation is well illustrated by the topographically significant White River Uplift in the eastern part of the basin and the Douglas Creek Arch in the western part of the basin. This compressional stage produced active subsidence and created the highly asymmetric geometry of the present-day Piceance Basin syncline. Some shallow flower structures are observed in the central part of the basin and indicate minor strike-slip deformation during the Cenozoic.

AAPG Search and Discovery Article #90156©2012 AAPG Rocky Mountain Section Meeting, Grand Junction, Colorado, 9-12 September 2012