AN INTEGRATED CARBON SEQUESTRATION DEPLOYMENT TEST AT DECATUR, ILLINOIS

In May, 2009, the Midwest Geological Sequestration Consortium (MGSC) completed drilling a 7,230 ft carbon dioxide injection well at Decatur, Illinois as part of the U.S. Department of Energy’s Regional Carbon Sequestration Partnership program. The well, targeting the Cambrian Mt. Simon Sandstone, will take 1,000 tonnes/day of supercritical CO₂ for three years beginning around April 2010. The well is the first UIC Class I Nonhazardous injection well of its type in the U.S. and its development culminates more than five years of regional and site specific geologic studies in the Illinois Basin. The site is developed at the Archer Daniels Midland (ADM) Company’s agricultural products facility and the CO₂ will be supplied by ADM as a byproduct of fuel ethanol production.

The Mt. Simon at the site is around 1,650 ft thick and is overlain by about 500 ft of Eau Claire Shale, consisting of shale, siltstone, and carbonates, that will serve as the reservoir seal. Early modeling of CO₂ injection has shown that even 100 years after injection of 1 million tonnes, the buoyant CO₂ plume has not reached the top seal. Extensive core, sample, and log data analysis is underway to evaluate injectivity, define perforation strategies, model the CO₂ plume, develop monitoring plans for a second well to be drilled about 600 ft away, and predict rock/brine interactions. Extensive environmental monitoring of groundwater, soil gas, and air has been implemented above the plume and around the site. Most importantly, the second well will be specially designed by Schlumberger Carbon Services for sampling fluid chemistry and pressure in the Mt. Simon and in the first porous zone above the Eau Claire seal as injection proceeds.

Geophysics will be used extensively to monitor the CO₂ plume. A 3,500 ft well will be drilled and a permanently installed geophone string will allow repeat acquisition of vertical seismic profiles (VSPs) to monitor plume development. A full baseline 3D seismic survey will be acquired in November 2009. Repeat VSPs will define the plume margin as injection proceeds. Geophysics, combined with a possible third monitoring well, and a two-year monitoring period after injection ceases will allow unprecedented understanding of subsurface CO₂ behavior and the safety and effectiveness of carbon sequestration in saline reservoirs.