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Reservoir-scale analysis of fluvial sand-body dimensions, distribution, and connectivity in a high net-to-gross system, Upper Williams Fork Formation, Main Canyon, Piceance Basin, Colorado

Nicholas K. Sommer,

Department of Geological Sciences, University of Colorado,

Boulder, Colorado 80309-0399,

[email protected]

This study involves the analysis of fluvial sand-body dimensions, distribution, and associated connectivity based on well-exposed outcrops of the Upper Williams Fork Formation located in Main Canyon, western Colorado (U.S.A.). The fluvial sandstones of this study were deposited by braided streams within a high net-to-gross ratio (50-80%) system. Exposures of the Upper Williams Fork Formation in this area of the Piceance Basin are outcrop analogs for equivalent braided-stream deposits that form subsurface petroleum reservoirs in the Piceance Basin and elsewhere.

Exposures of the Upper Williams Fork Formation in Main Canyon extend for more than 4 miles laterally and over 800 feet vertically. Aerial lidar and orthophotos have been acquired for the study area and provide outcrop images to define sand bodies and quantify their dimensions. Measured sections, paleocurrent data, and outcrop photomosaics will augment the lidar and orthophoto data set and aid in describing sand-body characteristics. These data will also provide information on internal sand-body heterogeneity. Among the results of this study will be a database of fluvial sand-body geometries and dimensions that will provide useful constraints for geoscientists to use for 3-D geologic modeling of equivalent petroleum reservoirs.

AAPG Search and Discovery Article #90060©2006 AAPG Foundation Grants-in-Aid