A PLAY-BASED EXPLORATION OF CO2 STORAGE IN THE ILLINOIS BASIN (Invited Presentation)

The Illinois Basin (ILB), with the nation’s first commercial Carbon Capture and Storage (CCS) project in Decatur, Illinois, has among the largest carbon dioxide (CO₂) storage resources in the United States. To support the development of these CO₂ storage resources, the Illinois State Geological Survey (ISGS) has conducted numerous site-specific characterization studies throughout the ILB for both storage facilities at stand-alone, point-source CO₂ emitters and carbon management hubs. Early CO₂ storage studies focused on the Cambrian Mt. Simon Sandstone (MtS), an ILB natural gas storage resource and Proved Developed CO₂ Storage Capacity at Decatur; therefore, the MtS is the first consideration of CCS project developers. However, with competition for MtS storage among projects and regional variations in reservoir quality, other Cambro-Ordovician formations are being assessed for CO₂ storage.

To support the assessment of CO₂ storage in Cambro-Ordovician formations, the ISGS is building and testing an integrated geospatial database for play-based exploration and analysis to map areas with high potential for CO₂ storage site development. Given the wide geographical distribution of 188 stand-alone, point-source CO₂ emitters in Illinois (NATCARB, 2023), this database will drive the play analysis to find porous sandstones and discrete porous intervals within otherwise low-porosity carbonates of the Cambro-Ordovician strata. The challenge is to high-grade the most promising areas with consideration given to all Cambro-Ordovician formations.

The play analysis uses existing subsurface data (e.g., wells, seismic surveys, maps, and models) developed through numerous ISGS site-specific and regional studies. Land surface (e.g., political boundaries, public infrastructure, CO₂ emitter locations) and societal data (e.g., disadvantaged communities, environmental burdens, place factors that may impact social support for CCS) from public sources are also used. These disparate datasets are combined into an integrated geospatial database to support the classification and categorization of stacked CO₂ storage resources that is expected to reduce exploration risk and expense, create investment assurance, and allow future studies to focus on the most promising sites.