October 12-17, 2025
In the Williston Basin, North Dakota, the Inyan Kara Formation (early Cretaceous) is the primary subsurface injection zone for produced water. It is comprised of extensive sandstone aquifers overlain by widespread shales of the Skull Creek Formation, resulting in large potential for saltwater disposal (SWD). It is also considered a potential geologic sequestration unit for carbon capture and storage (CCS). This subsurface aquifer is equivalent to the Lakota and Fall River Formations (Inyan Kara Group) that outcrop in the Black Hills of South Dakota and Wyoming.
The Black Hills outcrops provide an important analog for the types of stratigraphic and sedimentologic relationships expected within the Inyan Kara sequences in the subsurface of the Williston Basin. Four regions of the Black Hills outcrop study area have been chosen for this field workshop. The workshop itinerary has been constructed to allow participants to examine the heterogeneity of the Inyan Kara Group from proximal to more distal settings, along an approximately 160 km long, SE-NW transect. Beyond the specific benefits to Williston Basin activities, the outcrops provide a window into the broader geological history of the Western Interior Seaway, showcase a diverse range of sedimentary environments and deposits, and provide important insights for analogous systems in other basins and settings. An extensive library of done-based, 3D photogrammetry images (earth models) of the outcrops is available.
Inyan Kara Field Trip Agenda and Stops PDF
Workshop Background PDF
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