Carbon Dioxide Sequestration in Illinois Basin Coal

David G. Morse¹, Andrew Anderson¹, Scott Frailey¹, Maria Mastalerz², John Rupp², and Satya Harpalani^3
1Illinois State Geological Survey, Champaign, IL
²Indiana University, Indiana Geological Survey, Bloomington, IN
³College of Engineering, Southern Illinois University, Carbondale, IL

Initial research on coals within the Illinois Basin, the largest bituminous reserve in the United States, indicates that relatively thin and deeper coals have a significant capacity for sequestering CO₂. This capacity is being assessed at a demonstration project currently being developed in southeastern Illinois as part of the DOE’s Regional Partnership program. The main objective of this test is to determine the behavior of CO₂ on coal during injection and storage. The targeted Springfield Coal is 7 ft thick, 900 ft deep, and has a methane gas content of between 150 and 200 scf/ton. Desorbed Springfield Coal gases (vol % on a normalized air-free basis) are 88-96% methane, 2-9% nitrogen, 1-3% CO₂ with trace amounts of C₂₊. The carbon and hydrogen isotopes of the methane indicate primarily a biogenic origin.

One injection well and two observation wells oriented relative to the cleat directions are spaced approximately 50 to 150 ft apart based on pressure transient testing and modeling. Up to 600 tons of gas-phase CO₂ are available for injection over a period of 40-80 days, depending on injectivity. Reservoir simulation using COMET 3 has been used to determine well spacing, track anticipated CO₂ movement and to evaluate enhancing coalbed methane potential. DST’s, pressure transient analyses, and pulse tests have been used to determine the coal permeability. Lab measurements of CH₄, CO₂ and N₂ adsorption capacities, as well as coal shrinkage and swelling accompanying methane removal and CO₂ adsorption, respectively, have been completed. In addition, changes in the mesopore and micropore characteristics (specific surface areas, volumes, and size distribution) as a result of CO₂ adsorption have been analyzed in coals of varying petrographic composition.

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas