Integrated outcrop and subsurface geomodeling of the Turonian Wall Creek Member of the Frontier Formation, Powder River Basin, Wyoming, USA

Nathan M. La Fontaine, Tuan Le, Todd Hoffman, Michael H. Hofmann

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Inter-well heterogeneities influencing fluid migration in deltaic reservoirs are controlled by lateral lithofacies changes and vertical complexities such as low permeability thin-beds (i.e. mudstones). Subsurface tools cannot adequately predict the spatial and stratigraphic organization of these architectural elements, nor their influence on effective reservoir properties and connectivity. Our outcrop-based geomodeling study of the Turonian Wall Creek Member of the Frontier Formation in the Powder River Basin, Wyoming, USA, integrates subsurface production and flow simulation data to quantify the impact of multi-scale stratigraphic heterogeneity on analogous reservoir behavior and horizontal well design. The upscaled representation of thin-bed complexity in our 500 m × 715 m x 15 m geomodel is derived through flow simulation of internally nested, facies specific, centimeter-scale models (basic depositional element models or BDEMs). These BDEMs are populated with quantitative data of mudstone thin-bed geometries directly derived from digital outcrop measurements and measurements in the field, and aided by subsurface (core) petrophysical properties. Reservoir simulations are performed using various landing zone and completion configurations, and under both single-phase and multi-phase flow conditions history matched to subsurface production data. Results from our workflow demonstrate that, in heterolithic settings, the permeability of mudstone thin-beds impart the most significant impacts toward upscaled reservoir behavior, and deliver unique Kv/Kh flow anisotropies dependent on the governing depositional environment. Thin, laterally continuous and planar mudstone beds in the wave-and river-dominated distal delta front setting have the greatest negative effect on Kv and a minimal impact on Kh, promoting laterally continuous and vertically baffled flow units. Conversely, the more curvilinear and intersecting architectures of mudstone beds in the tidal dune facies maintain better vertical connectivity but decreased Kh compared to the wave-influenced facies. Reservoir flow is only sensitive to changes in engineering design (landing zone, well orientation, completion size) where thin-beds act as complete barriers rather than baffles to flow. Layer cake subsurface models failing to account for high-resolution stratigraphic architectures are likely to overestimate reservoir production where thin-beds act as barriers capable of appreciable reservoir compartmentalization, which in our models is more characteristic of the distal delta front setting. Synthesized results of this study are immediately applicable toward development planning in similar tight sandstone reservoirs.

Original languageEnglish
Article number104795
JournalMarine and Petroleum Geology
StatePublished - Mar 2021


Funding for this research was provided by SM Energy. Thanks to Mike Arthur and John Zupanic for their assistance in the field and in the lab. We are grateful to David Largent for allowing us land and outcrop access. Thoughtful reviews by Giancarlo Davoli and an anonymous reviewer helped to significantly improve this manuscript and are recognized with our greatest appreciation.

FundersFunder number
SM Energy


    • Deltaic
    • Facies heterogeneity
    • Fluid flow
    • Low permeability reservoirs
    • Reservoir characterization
    • Thin-bed heterogeneity
    • Unconventional
    • Upscaling


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