Washington, D.C. — The recent completion of a three-dimensional (3-D) seismic survey at a large Illinois carbon dioxide (CO2) injection test site is an important step forward for the carbon capture and storage (CCS) project’s planned early 2011 startup.
The survey – essential to determine the geometry and internal structures of the deep underground saline reservoir where CO2 will be injected – was completed by the Midwest Geological Sequestration Consortium (MGSC), one of seven regional partnerships created by the U.S. Department of Energy (DOE) to advance CCS technologies nationwide. CCS is seen by many experts as a key technology for reducing greenhouse gas emissions and helping to mitigate potential climate change.
The project, located in Decatur, Ill., will capture CO2 from the Archer Daniels Midland (ADM) Ethanol Production Facility and inject it into a deep saline reservoir, more than a mile underground. Starting in early 2011, up to 1 million metric tons of CO2 from the ADM facility will be compressed to a dense, liquid-like state and injected over a 3-year period. The rock formation targeted for the injection is the Mt. Simon Sandstone, at a depth between 6,400 and 7,000 feet. The Mt. Simon Sandstone is the thickest and most widespread saline reservoir in the Illinois Basin, with an estimated CO2 storage capacity of approximately 30–110 billion metric tons.
During a seismic survey, sound waves generated at the surface travel down through the ground and encounter underlying rock structures that reflect some of the waves back to the surface. These reflected waves are processed to generate clean, high-resolution 3-D images of the subsurface, providing greater detail of the structural and stratigraphic configuration of the rocks.
Analysis of the survey data is a key component in the comprehensive monitoring program that will be implemented to ensure the injected CO2 is stored safely and permanently. In addition to providing greater structural and stratigraphic detail, the survey data serves as a baseline for reservoir and fluid distribution within the Mt. Simon and shallower zones prior to injection operations. The survey data will also provide important information in identifying any fault networks in and above the injection zone, and will be used to predict where additional geophysical surveys should be deployed as CO2 is injected. Data acquisition of the 3.82 square-mile survey started on November 19, 2009, and was completed on January 31, 2010.
The seven DOE regional partnerships form a nationwide network that is investigating the comparative merits of numerous CCS approaches to determine those best suited for different regions of the country. MGSC is investigating options for the 60,000 square mile Illinois Basin, which underlies most of Illinois, southwestern Indiana, and western Kentucky. Emissions in this area exceed 304 million metric tons of CO2 per year, mostly attributed to the region's 126 coal-fired power plants.
DOE’s National Energy Technology Laboratory (NETL) manages the Regional Carbon Sequestration Partnership program.