Illinois Basin oil fields have an estimated CO2 storage resource of 140 to 440 million metric tons, 58 to 180 million metric tons of which are in reservoirs with conditions suitable for miscible CO2-EOR (Finley, 2005). Untapped reserves remain locked in established mature oil fields as well as prospective greenfields waiting for development. CO2-EOR recovery in the ILB has the potential to be economically significant by improving oil recovery and providing possible storage of anthropogenic CO2, and CO2-EOR reservoirs could potentially be co-located (stacked) with saline storage options. CO2-EOR interests in the wider region may assist the economics of a storage project long-term, via potential revenue from sale of CO2 for EOR and/or by taking advantage of Carbon Capture and Storage (CCS) tax credits under 26. U.S. Code § 45Q (and 2018 FUTURE Act amendments). Pilot scale injection tests have been performed at a few locations across the ILB with positive indications of oil response, but there have been no field-scale applications of CO2-EOR in the ILB. Enhanced ILB oil field miscibility classification maps show additional reservoir-level detail and help expand the screening area for CO2-EOR opportunities in the East Sub-Basin. Examination of the oil fields and their productive reservoirs revealed the presence of several carbonate and siliciclastic candidates for miscible/near miscible and immiscible CO2-EOR in the East Sub-Basin study area. In addition, related studies have identified and assessed residual oil zones (ROZs) in sandstone and carbonate formations throughout the region. These results and ongoing work highlight key reservoirs in primary fields of interest and provide the basis for targeted oilfield and site-specific work in assessing the feasibility of industrial-scale CO2 storage and CO2-EOR in the Illinois East Sub-Basin study area.