Hydrocarbon Potential of Upper Devonian Black Shale, Eastern Kentucky

Ian M. Johnston, Wayne T. Frankie, Jack R. Moody, Julie R. Kemper, Robert R. Elkin

The gas-producing Upper Devonian black shales of eastern Kentucky represent cycles of organic units alternating with less-organic units that were dominated by an influx of clastics from a northeastern source. This pattern of sedimentation is typical throughout the southern Appalachian basin in areas basinal to, yet still influenced by, the Catskill delta to the northwest. These black shales, which thin westward onto the Cincinnati arch, dip eastward into the Appalachian basin.

To evaluate the future gas potential of Devonian shale, a data base has been compiled, consisting of specific geologic and engineering information from 5,920 Devonian shale wells in Letcher, Knott, Floyd, Martin, and Pike Counties, Kentucky. The first successful gas completion in eastern Kentucky was drilled in Martin County in 1901.

Comparison of initial open-flow potential (IP) and long-term production data for these wells demonstrates that higher IP values generally indicate wells of higher production potential. Areas of higher IP are aligned linearly, and these lineaments are interpreted to be related to fracture systems within the Devonian shale. These fractures may be basement influenced.

Temperature log analyses indicate that the greatest number of natural gas shows occur in the lower Huron Member of the Ohio Shale. Using both the temperature log to indicate gas shows and the gamma-ray log to determine the producing unit is a workable method for selecting the interval for treatment.

AAPG Search and Discovery Article #91041©1987 AAPG Eastern Section Meeting, Columbus, Ohio, October 7-10, 1987.