Meal time at C. T. Lupton's U.S. Geological Survey field camp, circa 1910.  Photograph courtesy of the family of C. T. Lupton.

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ABSTRACT

Numerical waterfloods are simulated within two- and three-dimensional (2-D and 3-D) permeability structures developed for the Ivie Creek area along the Ferron Sandstone (Cretaceous) outcrop belt. Permeability structures are constructed by combining outcrop facies architecture data with permeability measurements made on both outcrop and drill-core samples. Simulated waterfloods are used to explore: (1) how detailed, fluvial-deltaic facies-derived permeability structures might influence oil production, and (2) the ability of different permeability upscaling approaches to capture the impact of the detailed structures on oil production. Permeability values incorporated in the models range from 0.1 to 50 millidarcies. The role of facies architecture is preserved in the 2-D gridded models (grid blocks are 2.5 ft long and 0.5 ft high) by assigning facies-related permeability trends within amalgamations of distinct clinoform bodies separated by thin shaley bounding layers. Results of a series of 2-D numerical waterflood simulations illustrate the sensitivity of total oil production and the timing of water breakthrough to the nature of the thin, interclinoform, shaley bounding layers. Permeability upscaling experiments indicate that common averaging approaches (computing arithmetic, harmonic, or geometric means) are inadequate to upscaling permeability in this fluvial-deltaic setting. An upscaling technique based on perturbation analysis yields 2-D simulation results similar to those obtained with detailed permeability models. Detailed permeability structures are upscaled and assigned in more coarsely gridded 3-D models (grid blocks are 20 ft by 20 ft in plan and 4 ft thick) by defining permeability facies that encompass portions of adjacent clinoform bodies. Results of a series of 3-D numerical waterflood simulations with 5-spot and 9-spot production well patterns illustrate the significant impact that the upscaled permeability facies geometry exerts on oil production. Comparing 2-D and 3-D simulation results confirms that it can be misleading to use 2-D simulation results to predict oil recovery and water cut in a reservoir with the internal 3-D geometry inferred at the Ivie Creek site.