Sequestration Potential in the Illinois Basin Coal Beds
Drobniak, Agnieszka 1, Korose, Christopher 2, Mastalerz, Maria 1, Moore, Thomas R. 2, and Rupp, John 1
1Indiana Geological Survey, Indiana University, 611 North Walnut Grove, Bloomington, IN 47405-2208
2Illinois State Geological Survey, 615 E. Peabody Dr., Champaign, IL 61820
Maps of extent, thickness, depth, and elevation have been created for seven major coal beds in the Illinois Basin, including: Danville, Hymera/Jamestown/Paradise, Herrin, Springfield, Survant, Colchester, and Seelyville/Davis/Dekoven. Additional maps (e.g. temperature, pressure, heating value) were also generated to assess the phase of the CO2 being sequestered. The temperature range of 65 to 85oF and pressure range 225 to 600 psi in the coal beds indicate a gaseous phase for the potentially sequesterable CO2.
Coal thicknesses, areal extents, as well as other mapped and measured parameters were used to estimate: a) in situ adsorbed coal-bed methane content, b) amount of CO2 that can be adsorbed onto the coal matrix, c) free phase CO2 that can reside in the cleats, and d) CO2 that can be dissolved in formation water. Where the areal distribution of coal quality data was sparse, high, medium, and low probabilistic values were selected from the distribution of measured values to put key variables into the equations, encompassing the range of uncertainty associated with these data. The volumetric equations were incorporated into a cellular GIS model for each coal bed map layer, and the results were summed to obtain the basin-wide estimates of CO2 sequestration. Our preliminary volumetric calculations suggest that the combined volume available in the coal beds within the basin is 3.5 billion metric tones of CO2. These values are preliminary estimates only, since numerous parameters that are important for CO2 adsorption (for example, maceral composition, cleats distribution and pore characteristics) are poorly documented. Moreover, the gaseous state of CO2 within this low pressure/temperature range occurring in the coal beds of the Illinois Basin raises concerns about the feasibility of CO2 storage in these relatively shallow coals. These concerns include: stability and effectiveness of CO2 adsorption, reactivity of CO2 with macerals and other surrounding mineral phases, and possibility of gas leakage and migration.