Pre-Knox sandstones and carbonates produce in less than 100 wells, nearly all located in eastern Kentucky. Shallow Shelf Carbonate Plays Nearly 10,000 wells in the Mississippian Greenbrier-Newman Limestone play have produced 2.9 tcf from the drillers' Greenbrier Big Injun, Keener and Big Lime reservoirs. Gas is produced from the Ordovician Trenton Limestone in both stratigraphic and structural traps in Kentucky and New York. Reef and Carbonate Bar Plays Gas wells have been completed in the Lower Mississippian Ft. Payne Formation in seven counties in Tennessee and four counties in adjacent Kentucky.
Production is associated with oil in most areas, with reservoirs developed in carbonate mounds.
Gas production in the Middle Devonian Onondaga Limestone reef play is from Edgecliff Member pinnacle reefs up to 200 feet high that cover up to 100 acres. Gas is produced from the Upper Silurian Lockport Dolomite and underlying Keefer Sandstone in numerous small fields in eastern Kentucky, and from the Lockport in northern Ohio. Plays Due to Unconformities and Structure Production from the Lower Devonian Oriskany Sandstone updip permeability pinchout play is confined to the western and northern margins of the basin. Good potential exists to extend the play northward into Ohio. The Cambro-Ordovician Knox Group unconformity play is more extensive, with production occurring in a broad trend along the western and northern margin of the basin from Tennessee to New York.