Subsurface Analyses of the Bedford-Berea Petroleum System in Eastern Kentucky

Abstract

The Berea Sandstone is a Late Devonian, tight oil and gas reservoir that has gained new interest with the advent of horizontal drilling. The sandstone is actually a siltstone over much of its extent, which complexly interfingers with Bedford Shales. This study utilized subsurface well data and core and previous outcrop descriptions to map the interval's distribution, evaluate potential structural influences, and attempt to differentiate the Berea Sandstone from the Bedford Shale.

To evaluate the Bedford-Berea interval, 555 geophysical well logs from the Kentucky Geological Survey's oil and gas database were used to generate structure maps, isopachs, and cross sections of the Bedford-Berea interval and its possible hydrocarbon source rocks the Sunbury Shale above, and the Ohio Shale below. To differentiate the Berea Sandstone from the Bedford Shale, five core descriptions were correlated to gamma-ray logs to establish an API cutoff for Berea coarse siltstones and sandstones on subsurface gamma-ray logs. A Berea isolith map was then generated utilizing the API-cutoff parameter.

The Bedford-Berea has an elongate, north-south-oriented thickness trend that cuts across basement structures subparallel to the interpreted paleoshoreline of the Berea to the east in West Virginia. This trend is different than both the underlying and overlying source rocks. Within the elongate trend, areas of thicker Berea occur on a (1) structural high north of the Kentucky River Fault System and east of the Waverly Arch, (2) along the Irvine-Paint Creek Fault System including the Wallbridge Fault, (3) along the Rockcastle River and Warfield Faults (and uplifts) on the southern end of the Rome Trough, and on the Pike County Uplift, especially along the flanks of the D'Invilliers structure.

The association of thicker Berea facies with structural highs in eastern Kentucky suggests structural influences on deposition, and either (1) reverse movement on some basement structures or (2) differential compaction of Bedford Shales and truncation by Sunbury transgression.

AAPG Datapages/Search and Discovery Article #90258 © 2016 AAPG Eastern Section Meeting, Lexington, Kentucky, September 25-27, 2016