Outcrop Characterization of Low-Accommodation Fluvial-Deltaic Reservoir Analogs: Field Guide to Selected Outcrops of the Lower Cretaceous Fall River Formation, Black Hills of South Dakota and Wyoming


Hydrocarbon recovery efficiency is controlled by reservoir heterogeneities resulting from geometric arrangements of strata, or "stratal architecture." Maximizing recovery requires an increased understanding of geologic processes that govern stratal architecture. Reservoir characterization studies integrate geologic descriptions of reservoir architecture with reservoir engineering to more effectively recover hydrocarbons. Fluvial-deltaic strata form the most heterogeneous class of siliciclastic reservoirs, with an average recovery efficiency ranging from 24 to 69% and averaging 40% (Galloway and others, 1988). Accordingly, it is of particular interest to determine controls on stratal architecture in fluvial-deltaic reservoirs.

Traditional reservoir characterization relates depositional systems to variations in stratigraphic architecture (Fisher and others, 1969). Depositional systems are a three-dimensional linkage of contemporaneous facies assemblages that are governed by a common suite of depositional processes (Brown and Fisher, 1977). This approach has provided important insights but fails to view heterogeneities within a stratigraphic context.


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