The Illinois Basin – Decatur Project (IBDP) is being carried out by the Midwest Geological Sequestration Consortium (MGSC), led by the Illinois State Geological Survey (ISGS) at the University of Illinois. The MGSC is one of the US Department of Energy's Regional Carbon Sequestration Partnerships designed to evaluate the safety and effectiveness of geological storage of carbon dioxide (CO2) as a mitigation tool to address global climate change. The MGSC team includes the ISGS, Schlumberger Carbon Services, and the Archer Daniels Midland Company (ADM) of Decatur, Illinois. ADM operates an agricultural product processing facility in Decatur, Illinois, at which 1 million tonnes of carbon dioxide (CO2) derived from the production of fuel ethanol is captured and injected into a deep saline reservoir, the Mount Simon Sandstone, at a rate of 1000 tonnes/day. Injection began in November 2011 and is scheduled for completion in November 2014. The site was selected after extensive geological screening work throughout the Illinois Basin. The lower third of the Mount Simon Sandstone contains bedload fluvial deposits with excellent reservoir quality; capacity, injectivity, and containment are meeting expectations. The IBDP incorporates extensive subsurface and surface monitoring, which integrates the injection well, a deep monitoring well, a geophysical monitoring well, and numerous shallow groundwater wells and surface monitoring sites. Multiple disciplines in geology, reservoir engineering, geophysics, outreach and education, reservoir modeling, hydrology, geochemistry, basin analysis, seismology, data management, chemical engineering, facilities construction, and field operations have combined to make IBDP a viable project.

a b s t r a c tThe Illinois Basin-Decatur Project safely and successfully injected, over three years, nearly 1.1 million tons (1 million tonnes) of supercritical carbon dioxide (CO 2 ) into the base of a 1640 ft (500 m) thick saline sandstone reservoir at a depth of 7025 ft (2.14 km). The injection interval, with its high porosity and permeability, allowed for injection pressures to be far below fracture pressures during the daily 1102 tons (1000 tonnes) injection rate. Microseismicity was monitored 1.5 years before injection, through the 3 years of injection and now during permanent shut-in which began in November 2014. The overall average of locatable events per day, during injection, was a little over 4, and events appear to be related to development on previously undetected planes of weakness. Some of these planes and active areas may be related to features developed during diagenetic or compactional processes associated with the Precambrian surface topography. Microseismicity during transient shut-in did not show a rate of decrease, large changes in magnitude, distance from the injection well, or depth.