Facies analysis of the Prairie du Chien group in the Illinois Basin and analogous rocks in Missouri and Kentucky

Ali, Shah Bilawal

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https://hdl.handle.net/2142/129976 Copy

Description

Title

Facies analysis of the Prairie du Chien group in the Illinois Basin and analogous rocks in Missouri and Kentucky

Author(s)

Ali, Shah Bilawal

Issue Date

2025-07-23

Director of Research (if dissertation) or Advisor (if thesis)

Best, James L

Committee Member(s)

Fouke, Bruce W

Department of Study

Earth Sci & Environmental Chng

Discipline

Geology

Degree Granting Institution

University of Illinois Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Facies Analysis
• Prairie du Chien Group
• Carbon Capture and Storage (CCS)
• Reservoir Characterization
• Mixed Carbonate-Siliciclastic Ramp
• Paleokarst
• Diagenesis, Porosity and Permeability
• Core Description
• Thin Section Analysis
• Outcrop Analogs
• Illinois Basin

Abstract

The injection of supercritical carbon dioxide (scCO₂) into deep saline aquifers has emerged as a key strategy for mitigating rising atmospheric CO₂ concentrations and resulting global warming. Funded in 2023 by the U.S. Department of Energy’s Phase II Carbon Storage Assurance Facility Enterprise (CarbonSAFE) initiative, a Heidelberg Materials cement plant in Mitchell, Indiana, is currently being evaluated as a potential Carbon Capture and Storage (CCS) subsurface injection site. Prior to construction of this commercial-scale CCS site, a detailed geologic characterization of the storage complex is required to assess the feasibility of long-term sequestration and support a Class VI permit application through the State of Illinois Department of Natural Resources. The Heidelberg CCS project targets the middle to upper Prairie du Chien Group (Early Ordovician) in southwestern Indiana. Assessment of reservoir feasibility requires collection of field data, seismic surveys, well-log correlation, geologic modeling, characterization well drilling, well testing, and reservoir simulation. However, the proposed Heidelberg CCS site is in a data-limited region, lacking both outcrop analogs and deep wells penetrating the target interval, which makes geologic modelling difficult prior to drilling a characterization well. To directly address this problem, the present study was undertaken to understand the sedimentologic composition and stratigraphic architecture of the Prairie du Chien Group from analogous outcrops and cores in the Illinois Basin and adjacent regions. Fieldwork on outcrops at five sites near Rolla, Missouri, and two sites in Franklin Grove and Sheridan, Illinois, were combined with core studies from the Criswell (API #121370034900, Morgan County, Illinois) and Marvin Blan #1 (IGSN #IEKGS003F, Hancock County, Kentucky) wells. This combination of surface and subsurface coverage permitted characterization of the facies composition, stratigraphy and lateral distributions. Sixty thin sections from field and core samples were analyzed petrographically to assist in determining the depositional and diagenetic history of each subsurface unit, assign depositional facies, and combine thin section-based estimates of porosity with NER TinyPerm 3 estimates of permeability. Results have identified 14 unique facies (F) that have been grouped into four recurring facies associations (FAs), which include: 1. FA1 (Peritidal): comprising laminated dolomudstone (F1), green claystone (F2), stromatolite boundstone (F3), and thrombolite boundstone (F4). 2. FA2 (Siliciclastic Shoreline): comprising parallel- to ripple-laminated quartzarenite (F5), planar cross-bedded quartzarenite (F6), and quartzarenite with interbedded clay (F7). 3. FA3 (Shallow to Deep Subtidal): comprising sandy-intraclast/bioclast dolowackestone (F8), sandy-ooidal-intraclast dolowackestone to dolopackstone (F9), and sandy-ooidal dolograinstone (F10). 4. FA4 (Paleokarst): comprising matrix-rich breccia (F11), clast-supported breccia (F12), mosaic breccia (F13), and crackle breccia (F14). These facies and facies associations were deposited on a mixed carbonate-siliciclastic ramp in a restricted shallow marine setting under arid, hypersaline, and locally anoxic conditions. Primary porosity in the middle to upper Prairie du Chien Group is predominantly intergranular to intercrystalline. However, significant generation and occlusion of porosity is apparent due to dolomitization, sabkha-style evaporite reflux, mesogenetic diagenesis, and meteoric karstification during internal disconformities as well the Tippecanoe unconformity (~470Ma). Results suggest that there is significant storage potential in the siliciclastic shoreline (FA2) and paleocave (FA4) facies associations of the middle to upper Prairie du Chien Group due to their high porosity and permeability, which are suitable for CO₂ injection (F5 – 10% to 20% porosity, 292.25 mD horizontal permeability; F6 – 10% to 20% porosity, 221.29 mD horizontal permeability; F12 – 10% to >20% porosity, 79.69 mD horizontal permeability). However, the heterogeneous distribution of karst features may create preferential flow pathways, requiring careful reservoir modelling to understand plume migration, while the presence of clay and mud-rich interbeds in the sandstone facies may reduce effective permeability in some zones, necessitating a targeted injection strategy. Additionally, the dolomitic facies that were not karstified, particularly the laminated dolomudstones (F1), can function as effective baffles or local seals due to their low porosity and permeability (<5 % porosity and 18.87 mD horizontal permeability), helping to confine the injected CO₂ within the target reservoir. While these dolomudstones provide secondary containment, assurance of a regional seal for the CCS injection reservoir would depend on the integrity of overlying units like dolomitic intervals within the Ancell Group or shales of the Maquoketa Group.

Graduation Semester

2025-08

Type of Resource

Thesis

Handle URL

https://hdl.handle.net/2142/129976

Copyright and License Information

Copyright 2025 Shah Bilawal Ali

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