Stratigraphy, Sedimentology and Reservoir Modeling of the Late Devonian Berea Sandstone/Siltstone in northeastern Kentucky and southeastern Ohio

The Berea Sandstone is a Late Devonian unit that interfingers with and overlies the Bedford Shale. In the study area, the Bedford-Berea sequence averages 120 feet thick based on geophysical logs. The Bedford Shale makes up roughly 45 feet of the interval and the Berea Sandstone makes up the remaining 75 feet. Horizontal drilling and hydraulic fracturing have caused the Berea to become one of the largest oil producing formations in Kentucky to date. Depositional models proposed for the Bedford-Berea sequence fail to explain the vertical successions of sedimentary structures observed in outcrop and thickness patterns within the subsurface. Thus, an integrated outcrop and subsurface analysis of the Bedford-Berea sequence was conducted using 22 outcrops and 148 gamma ray/density logs in northeastern Kentucky and southeastern Ohio. Recent research into extrabasinal turbidites (hyperpycnites) has shown that similar vertical successions of sedimentary structures were produced by fluctuating flows. These vertical successions of sedimentary structures are observed in the Bedford-Berea sequence in outcrop and suggest hyperpycnal influence. Thus, the Bedford-Berea sequence represents wave influenced hyperpycnal and tempestites deposits, which were deposited in a prodelta to distal delta front setting where sediment was being derived from a northern fluvial/deltaic source. A better understanding of sediment dispersal, depositional conditions, and facies will help the oil and gas industry create more accurate reservoir maps within the study area. Furthermore, the presence of hyperpycnal facies within the Bedford-Berea sequence may explain sedimentary structures within other shallow marine deposits in southern Ohio and northeastern Kentuck