Geological Sequestration Test in Illinois Coal:
Field Site Selected and Work Begins

The Midwest Geological Sequestration Consortium (MGSC), led by the Illinois State Geological Survey (ISGS), along with the Indiana and Kentucky Geological Surveys and industry partners, including Gallagher Drilling Co., Inc. in Evansville, Indiana, have begun preparations for carbon sequestration in coal seams and potential methane recovery in western Wabash County, Illinois. Teaming geological sequestration of carbon dioxide (CO₂), one of the most promising strategies for reducing greenhouse gas emissions, with coal bed methane recovery could provide additional resource recovery in the Illinois Basin. Initial work is primarily aimed at understanding the injectability of CO₂ and the response of the coal.

Gallagher Drilling Co. helped ISGS staff find a lease owner whose acreage was suitable for the field test site. ISGS geologists visited the selected site and staked locations for potential injection and monitoring wells. Well permits were received from the Illinois Office of Mines and Minerals, and site approval was obtained from the U.S. Department of Energy.

The ISGS drilled two of three planned coal-coring wells in July. The wells will allow the ISGS staff to analyze the coals and model CO₂ injection prior to the May 2008 CO₂ injection test. Depending on the results of pressure falloff tests and a pulse test, a third and possibly a fourth well will be drilled later this year. The target coal in this field test is the Springfield Coal seam at a depth of 942 feet. The seam is six to seven feet thick, and the extensive Pennsylvanian shales of the Carbondale Formation above the coal should provide an adequate seal. The field test is projected to inject 600 tons of CO₂ over a period of approximately 30 to 60 days, depending on the permeability of the coal, during which time the CO₂, as it is adsorbed by the coal, is expected to displace coal bed methane toward the two observation wells. The test will measure changes in injectivity (injection rate and pressure) as CO₂ is pumped into the well.

The field test included the drilling of one injection well and two or three monitoring wells. The wells will be drilled in an L-shaped pattern parallel to the natural butt and face cleats (coal fractures) in the Springfield Coal. Geologists have cored multiple coals in the two wells drilled thus far. The core samples are being analyzed to determine their gas content, adsorption isotherms, and other coal parameters to be used for computer modeling of the sequestration process and the methane recovery potential. An extensive environmental monitoring, measuring, and validation (MMV) program will begin prior to injection of CO₂. Use of high-resolution infrared aerial digital imagery helped establish baseline land surface properties of the site. In the unlikely event of a leak, such imagery should allow detection of changes in the vegetation caused by interaction with CO₂. The MMV program also will include installation of groundwater and soil monitoring wells to measure the background levels of gas prior to CO₂ injection.

Gallagher Drilling Company of Evansville is the lease operator of the site and provides field, engineering and geologic support. Funding for this research is provided by the U.S. Department of Energy and the Illinois Department of Commerce and Economic Opportunity, Office of Coal Development.

Updated 9/17/2009 SLD