World class exposures of Upper Cretaceous strata in the Book Cliffs of east-central Utah provide outcrops that demonstrate the 3D reservoir architecture of marginal marine strata. These strata were deposited by a variety of depositional settings ranging from fluvial to incised valley to shoreface and deltaic. For those more comfortable with systems tracts, we observe features common to highstand shorelines and contemporaneous alluvial deposits, late highstand and lowstand shorelines, and incised valleys. We illustrate through the use of spectacular outcrops, subsurface datasets, and stratigraphic modeling how these systems tracts and key surfaces (flooding surfaces and sequence boundaries) may be recognized. The outcrops have almost complete exposure of over 500 m of strata in both depositional strike and dip sections that extend for over 200 km. Well logs and cores from the nearby oil and gas wells provide the opportunity to learn how to recognize outcrop relationships in more traditional subsurface datasets. This field seminar demonstrates how well log and core data can be used to predict reservoir geometries at both the exploration and production scales.
During the seminar, a practical approach of using sequence stratigraphic concepts is developed through the use of lectures, computer modeling, outcrop exposures and is reinforced through subsurface exercises. Field observations and data sets drawn from a variety of subsurface examples are used to develop understanding of vertical facies relationships that can be used to predict subsurface reservoir architecture in a variety of basin settings. At the end of the course, participants will have an understanding of deltaic and fluvial facies and the nature of larger scale stratigraphic variations within these deposits. Participants will be able to use these facies relationships to understand stratal stacking patterns that can be used to estimate lateral extent of reservoir facies. Participants will learn a process of how to use subsurface data to gain an understanding of depositional systems and key sequence stratigraphic surfaces to assist in either exploration or production.
The field trip begins by looking at the sedimentological and stratigraphic aspects of the Panther Tongue and lower Blackhawk Formation exposures in the vicinity of Price, Utah. In this relatively high-accommodation setting, sequence boundary unconformities are not developed and marginal marine facies tracts are more fully preserved. The high-accommodation stratigraphy in the vicinity of Price is contrasted with observations from the stratigraphically younger Desert Member of the Blackhawk Formation and the Castlegate Sandstone in the vicinity of Green River, Utah. In these deposits, subsidence rates are diminished relative to those found near Price; resulting in progradation during relative sea level fall which generated well developed sequence boundary unconformities. The stratal architecture of these deposits is dramatically different from the architecture associated with the more high-accommodation deposits near Price, Utah.