Stratigraphy and Resource Assessment of Mississippian and Devonian Oil Shales of Northeastern Kentucky: ABSTRACT

Abstract

Heightened interest in the organic carbon-rich shale of Mississippian and Devonian age as a source of oil has resulted in intensive leasing along the shale outcrop belt in Kentucky. Twelve cores of shale from Lewis and Fleming Counties were examined and analyzed in an effort to relate details of stratigraphy to the oil-rich horizons and to outline areas of minable potential resources. Formations of interest are the Sunbury Shale (Lower Mississippian) and the Ohio Shale (Upper Devonian). The generalized stratigraphy (Lower Mississippian through Upper Devonian) is, in descending order: Borden Formation, Sunbury Shale, Berea Sandstone, Bedford Shale, and Ohio Shale. Useful key markers in the sequence are the Three Lick Bed and the Foerstia zone, which are both in the Ohio Shale. The Three Lick Bed divides the Ohio Shale into the Cleveland Member, above, and the Huron Member, below. The Ohio Shale is underlain by Silurian Bisher Limestone and Crab Orchard Formation. Organic content is high in the Sunbury Shale and in the upper part of the Cleveland Member of the Ohio Shale. In cores, the total thickness of the Sunbury ranges from 12.0 to 18.4 ft (3.7 to 5.6 m). The combined thickness of Berea Sandstone and Bedford Shale ranges from 28 to 122 ft (8.5 to 37.2 m). The Cleveland shale ranges from 50 to 65 ft (15.2 to 19.8 m). Assuming a stripping ratio of 2.5 to 1, more than 2.9 × 106 acre-ft (3.6 × 103 cu hm) of shale having a Fischer-assay oil yield greater than 11 gal/ST (38 l/MT) is minable by means of existing methods. A conservative estimate of the amount of the potential strippable shale-oil resource in these two counties is more than 2 × 109 bbl. End_of_Article - Last_Page 897------------