Shale resource plays continue to be the most actively explored and developed hydrocarbon plays in North America. However, despite the intense activity surrounding the shale plays, understanding the controls on reservoir quality and successfully exploiting shale formations remains challenging. Using examples primarily from the Eagle Ford Formation, this paper demonstrates how inorganic whole-rock geochemical data can be used to help with the development of shale plays. Elemental data are used to provide regional stratigraphic correlations and provide sufficiently high resolution characterization to enable horizontal well-bores to be related back to pilot holes. The same elemental data used for chemostratigraphy can also be used to model mineralogy and total organic carbon, determine paleoredox facies and provide information on the formation brittleness, all valuable information in the exploitation of shale resource plays. The methodologies demonstrated here in the Eagle Ford Shale Formation have been used extensively in other North American shale plays and are readily applicable to any of the newly emerging shale gas resource play around the World.
Incised valleys are a ubiquitous feature of the Lower Cretaceous Mannville Group of the Western Canada Sedimentary Basin. The Basal Quartz, a member of the Lower Mannville Formation, is present in two north-south-oriented subparallel valley-form systems in southern Alberta, the western valley form termed the Taber-Cutbank Valley and the eastern valley form termed the Whitlash Valley. This paper details the application of chemostratigraphy to discriminate between the three informal lithostratigraphic units of the Basal Quartz, namely the Horsefly, the Bantry-Alderson-Taber (BAT), and the Ellerslie units in these valley forms. In the Taber-Cutbank Valley, the Horsefly, BAT, and Ellerslie units each have unique chemostratigraphic signatures that enable them to be readily differentiated using inorganic geochemical data. The changes in elemental chemistry that allow this differentiation are inferred to reflect changes in sediment provenance, paleoclimate, and surface residence time. The whole-rock geochemistry of the Horsefly unit, the basal unit of the fill, is demonstrated to remain relatively constant longitudinally in the Taber-Cutbank Valley, therefore demonstrating, when compared to the vertical changes in geochemistry, that temporal or stratigraphic changes are of a greater magnitude than longitudinal changes within in a single valley form. The whole-rock geochemistry of the Horsefly unit in the two valley forms, which in previous studies has been demonstrated to be homotaxial by conventional stratigraphic techniques, is markedly different between the two valley forms. The geochemical differences suggest that the Horsefly unit was subjected to more prolonged and/or intense weathering in the eastern Whitlash Valley than in the western Taber-Cutbank Valley, and that the provenance of the Horsefly unit is fundamentally different between the two valley systems. The application of chemostratigraphy to the Basal Quartz of the Lower Mannville Formation demonstrates that the technique can be utilized as a viable correlation tool in low-accommodation incised-valley settings; however, it is most effective when the whole-rock geochemical data are placed in a regional context by integration with a detailed stratigraphic framework. Once chemostratigraphy is used in conjunction with these other data streams, the differences in geochemistry of the Horsefly unit between the Whitlash and Taber-Cutbank Valleys can be used to infer that the Horsefly unit deposited in the two valleys are two homotaxial, not coeval subunits.
The URTeC Technical Program Committee accepted this presentation on the basis of information contained in an abstract submitted by the author(s). The contents of this paper have not been reviewed by URTeC and URTeC does not warrant the accuracy, reliability, or timeliness of any information herein. All information is the responsibility of, and, is subject to corrections by the author(s). Any person or entity that relies on any information obtained from this paper does so at their own risk. The information herein does not necessarily reflect any position of URTeC. Any reproduction, distribution, or storage of any part of this paper without the written consent of URTeC is prohibited.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.