UAS-DRIVEN ANALYSIS AND RESERVOIR MODELING OF THE WILLIAMS FORK FORMATION IN THE PICEANCE BASIN, COLORADO

This study presents a workflow to evaluate the fluvial architecture, lithological distribution, and static connectivity of sandstone reservoirs in the lower Williams Fork Formation. The analysis involves modeling outcrop data collected via a hyperspectral UAS from a representative outcrop in Main Canyon, Piceance Basin, Colorado.

The Upper Cretaceous lower Williams Fork Formation is characterized by a relatively low net-to-gross ratio (typically less than 30%) and consists of fluvial channels, crevasse splays, swamps, and floodplain deposits, formed by meandering river systems in a coastal plain environment.

The study utilizes UAS technology to generate three-dimensional models for defining the stratigraphic architecture and applies hyperspectral UAS data to map lithological variations in the outcrop. These data are then used to build three-dimensional reservoir models of the lower Williams Fork Formation, incorporating outcrop-derived information such as sandstone body types, dimensions, stratigraphic positions, and lithological distributions.

Results from the object-based modeling approach demonstrate that static connectivity of sandstone bodies is influenced by their width and the distribution of impermeable lithologies, such as mudstone and coal. These factors also affect the well spacing required for effective reservoir drainage or filling.

Due to the low sandstone reservoir proportion and limited continuity of the lower Williams Fork deposits, this research provides a practical workflow to generate reliable data and detailed sandstone body statistics. These insights support subsurface correlations and constrain depositional environments in subsurface reservoir modeling efforts.