Middle Devonian Dundee Formation carbonates are prolific hydrocarbon reservoirs throughout the Michigan Basin that have produced in excess of 375 million barrels of oil from more than 100 fields. There is limited fundamental understanding of the complex facies mosaics and stratigraphic architecture in this interval. This stratigraphic complexity is likely controlling the reservoir architecture in both lateral and vertical dimensions. The primary goal of this study was to develop a more detailed understanding of the stratigraphic architecture of the Dundee Formation in the South Buckeye field through utilization of closely spaced subsurface cores and accompanying wireline logs. Data on facies types, vertical stacking patterns, and variability within the field were then combined with modern and ancient analogs to develop the parameters to populate a series of three-dimensional (3-D) static geostatistical models. A fundamental question was to determine if the geographic distribution of patch reefs in the South Buckeye field could be accurately modeled with industry-standard geostatistical software (Schlumberger’s Petrel) based on core and wireline log data without a tie to 3-D seismic data. This study used geometrical data from multiple modern and ancient depositional analogs to constrain the geostatistical models. The geographic distribution and internal architecture of patch reefs were defined through the integration of petrophysical and high-density petrographic analyses from the subsurface core data.

Based on core, wireline log analysis, and depositional analogs, three end-member interpretations were modeled geostatistically and used to define the distribution and scale of the patch reef reservoirs in the South Buckeye field. As with many carbonate reservoirs, a 3-D static reservoir model is a critical step in the workflow for efficient hydrocarbon extraction, natural gas storage, and CO₂ sequestration, and this study provides insight into the Michigan Basin Dundee Formation patch reefs as well as possibly other Devonian carbonates and reef trends around the world.