ABSTRACT: The project was conducted by the Illinois Basin Consortium (IBC), consisting of the Illinois State Geological Survey, Indiana Geological Survey, and Kentucky Geological Survey, and was partially funded by the Gas Research Institute (GRI). The work consisted of compiling, updating, reviewing, and interpreting all available data relating to gas production and potential for the New Albany Shale in the three-state region. This project represents a more integrated basinwide approach to determine the gas production potential of the shale in the Illinois Basin than that employed in previous studies. Results of this study include a plate showing basinwide stratigraphic cross sections as well as the following six basinwide maps at a scale of 1:1,000,000: (1) major structural features of the Illinois Basin, (2) locations of cores of the New Albany Shale in the Illinois Basin, (3) elevation of the top of the New Albany Shale in the basin, (4) total thickness of the formation, (5) average initial potential (IP) for New Albany Shale gas fields, and (6) mean random vitrinite reflectance (Ro) for New Albany Shale samples in the Illinois Basin. Post-1980 gas production data on file at the three surveys, stimulation data for New Albany Shale wells, core location data, and mean random vitrinite reflectance (Ro) data are also included in the report. The New Albany Shale is predominantly an organic-rich brownish-black and grayish-black shale that is present in the subsurface throughout the Illinois Basin. It was estimated to contain 86 trillion cubic feet (TFC) of natural gas by the Devonian Shale Task Group of the National Petroleum Council Committee on Unconventional Gas Sources in 1980 and has produced gas for more than 100 years, mostly from western Kentucky and southern Indiana. Where the stratigraphy is known, the gas reservoirs are observed to be in the organic-rich brownish-black shales of the Grassy Creek (Shale), Clegg Creek, and Blocker (Shale) Members. Fractures provide the effective reservoir permeability in some zones and gas is stored in both as free gas in fractures and as absorbed gas on kerogen and clay surfaces. Limited data suggest that some gas fields are associated with faults, folds, and local and regional carbonate buildups over which the New Albany is draped, conditions that would favor the development of fractured reservoirs. The average IP from 60 fields ranged from 1 to 4,400 thousand cubic feet of gas per day (MCFGPD) resulting in a basinwide average IP of 187 MCFGPD. The Ro values for most New Albany Shale samples are low (less than 0.7 percent) and below the conventionally accepted range for the main state of thermal generation of natural gas (0.7-2.0 percent). Rock-Eval TMAX data indicate that some shale samples with Ro values as low as 0.41 percent have begun the natural process of thermal generation of hydrocarbons and that statistically any given organic-rich New Albany Shale sample may begin the generation of associated gas at Ro values of about 0.53 percent. Carbon isotope and composition data confirm that New Albany Shale gas is predominantly thermogenic, low maturity, and associated with oil generation. The correlations of geochemical and lithological attributes indicates that the gas is indigenous.
Hasenmueller, N. R., Comer, J. B. 1994, Gas potential of the New Albany Shale (Devonian and Mississippian) in the Illinois Basin: Illinois Basin Consortium Illinois Basin Study 02, 83 p., 19 fig.
Notes: 3 Appendices. Prepared by the Illinois Basin Consortium for the Gas Research Institute (GRI publication no. 92/0391).
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