USE OF THE SCINTILLOMETER AND GAMMA-RAY LOGS FOR CORRELATION FROM THE SUBSURFACE TO THE SURFACE IN BLACK SHALE.

Stratigraphic studies of the Devonian and Mississippian Ohio, Sunbury, New Albany, and Chattanooga Shales (consisting primarily of black, organic-rich shale) in the eastern portions of Ohio, Kentucky and Tennessee indicate that radioactive units evident on subsurface gamma-ray logs from oil and gas wells penetrating these formations can be distinguished in outcrops and in cores by using a scintillometer. Except for thin green-shale beds distributed throughout the black shale, exposures of the Ohio, New Albany, and Chattanooga Shales are lithologically homogeneous. Use of this technique has shown, however, that these black-shale formations contain seven major radioactive units, which can now be correlated with named surface and subsurface units.