Coalbed Methane Research Drilling in Illinois- New Data

Morse, David G., Demir, Ilham, Moore, Thomas R., and Elrick, Scott D.

Illinois State Geological Survey, Champaign, Illinois

Coalbed gas testing of major coals in two new wells drilled in eastern Illinois by the Illinois State Geological Survey (ISGS) indicate potential for commercial production in this evolving play.  The James Cantrell, #9 Hon well in northeastern White County cored seven coals totaling 24.5 feet from the Danville through Davis coals at depths from 756 to 1114 ft. Coal gas contents (dmmf) range from 78 to 129 scf/ton.  Desorbed gas compositions range from 60 to 82% methane, 16 to 37% nitrogen, and 1.2 to 2.0% CO₂. Methane saturation ranges from 40 to 64%.  Pressure transient tests in the Hon #9 coals indicate permeabilities of 3 to 200 md, with all but one value in the 3 to 35 md range.  A pilot production program will be developed here to evaluate water flush, nitrogen frac, and slickwater stimulation treatments with varying flow rates and amounts of proppant.

In southeastern White County, ISGS drilled 33 feet of coal in the Howard Energy, #C-1 Wassem well and cored 8 coals from the Danville to the Mt. Rorah at depths from 387 to 966 ft.  Gas contents range from 75 to 112 scf/ton (dmmf).  Desorbed gas compositions range from 69 to 96% methane, 0.5 to 31% nitrogen, and 1.2 to 2.8% CO₂.  Methane saturation ranges from 24 to 92%.  Carbon and deuterium isotopes suggest the desorbed methane from both wells is primarily biogenic in origin. Possible coal oxidation in canisters may have lowered methane and boosted nitrogen composition values for both wells.