298-2 Characterization of Potential Confining Units in the Cambrian Carbon System: Insights from the Eau Claire Formation, Michigan Basin

Session: Joint SGD-SEPM-IAS Focus on Sedimentary Geology and Energy Transitions (Posters)

Poster Booth No.: 120

Presenting Author:

Ashley Scott

Authors:

Scott, Ashley Brooke¹, Burns, Moira Aine², Copus, Max³, Trout, Jennifer⁴, Conner, Amber⁵, Haagsma, Autumn⁶, Kaczmarek, Stephen E.⁷

(1) Department of Geological and Environmental Sciences, Western Michigan University, Kalamazoo, MI, USA, (2) Department of Geological and Environmental Sciences, Western Michigan University, Kalamazoo, MI, USA, (3) Department of Geological and Environmental Sciences, Western Michigan University, Kalamazoo, MI, USA, (4) Western Michigan University MGRRE, Kalamazoo, MI, USA, (5) Michigan Geological Survey, Kalamazoo, MI, USA, (6) Michigan Geological Survey, Kalamazoo, MI, USA, (7) Department of Geological and Environmental Sciences, Western Michigan University, Kalamazoo, MI, USA,

Abstract:

The Eau Claire Formation is widely interpreted as a confining unit in numerous carbon capture, utilization, and storage (CCUS) studies and plays a critical role in the Cambrian carbon system across the Midwestern region of the United States. Although the confining capabilities of the Eau Clair have been the focus of numerous CCUS studies, particularly in the Illinois Basin, the lithologic, mineralogic, petrographic, and elemental heterogeneity remains largely unknown in the Michigan Basin. To address this gap, a high-resolution petrological assessment of the Eau Claire Formation was conducted using two wells in eastern and western Michigan with the goal of evaluating basin-scale facies variability and confining capabilities.

Detailed core-based lithologic characteristics and thin-section petrography were integrated to evaluate textural variability, pore types, mineral assemblages, and extent of cementation. X-ray fluorescence analyses, conducted at a 0.1 ft sampling interval, highlight elemental variability within each facies and support lithofacies delineation. Powder x-ray diffraction analyses further constrain mineralogical heterogeneity within representative facies. Collectively, these datasets provide the basis for a holistic understanding of lithologic, mineralogic, petrographic, and geochemical variability within the Eau Claire Formation.

The results reveal significant heterogeneity across the Michigan Basin, including lithologic variability (e.g., mudrock – sandstone), bulk rock mineralogy (e.g., illite, glauconite, potassium feldspar, quartz), grain size distribution (e.g., clay – coarse sand), visually estimated porosity (e.g., up to 15%), and extent of cementation (e.g., partially to fully occluded). Based on preliminary observations, the Eau Claire Formation has the potential to serve as a secondary storage/seep zone. These findings underscore the need for site-specific characterization and provide a foundation for evaluating the confining capability of the Eau Claire Formation. This research is funded by the U.S. Department of Energy (DOE) under DE-FE0032368.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10174

© Copyright 2025 The Geological Society of America (GSA), all rights reserved.