Abstract
This study presents facies descriptions and interpretations of the Eocene Sunnyside delta interval of the Green River Formation in Nine Mile Canyon, Utah, to document and constrain reservoir architecture and heterogeneity in lacustrine strata. Detailed measurement of vertical outcrop sections, paleocurrent directions, lithologic descriptions, and facies mapping of photopanoramas and digital Light Detection and Ranging (LIDAR) data were completed to define and interpret stratigraphic architecture at centimeter to meter scales. Results favor a depositional setting that fluctuated among delta plain (overbank, distributary channel, and mouth bar), marginal lacustrine, shoal water, and offshore lacustrine deposits. These strata were deposited at a distributary-dominated shoal-water deltaic margin and form four prograding parasequences that coarsen upward over the approximately 150 m (492 ft) thick study package. Measured channel dimensions and calculated sinuosities indicate a meandering fluvial system, and channel deposits include isolated lenticular, amalgamated lenticular, and amalgamated undulatory sandstones. Along with distributary mouth bar deposits, these channelized sandstone bodies represent the most promising reservoir units based on their lateral continuity and stacking geometries (ranging from 40- to 115-m [130- to 377-ft] wide 4- to 6.5-m [13- to 20-ft] thick), as well as measured porosity and permeability relationships. Quantified dimensions of sandstone bodies and characterization of their lateral and vertical connectivity are significantly aided by a digital outcrop model. This model was generated by groundbased LIDAR, and results were exported as spatial and geologic constraints for geocellular modeling. Such quantitative outcrop-based modeling provides guidelines for predicting subsurface reservoir quality and dimensions, and may be extrapolated to analogous fluviodeltaic and lacustrine hydrocarbon prospects