Berea Sandstone Horizontal Oil Play, Northeastern Kentucky

Presentation given November 2014: The Upper Devonian Berea Sandstone is a major natural gas and oil reservoir in eastern Kentucky. Oil and gas production dates back to the early 1900’s. Production is from stratigraphic traps in tight siltstone and very fine-grained sandstone reservoirs interpreted to have been deposited in turbidite fans and channels, and storm shelf environments. Recent activity has concentrated on shallow oil production in northeastern Kentucky. Since 2011, there have been 58 completions, mostly in Greenup and Lawrence Counties. Production ranges from 8 to 70 BOPD, 7 to 37 MCFD, and 10 to 114 BWPD. All completions are horizontal with multistage hydraulic fracture stimulation. True vertical depths range from 980 to 1,860 ft. Average laterals are 2,500 to 2,600 ft. long. Oil pay zones range from 10 to 30 ft thick. Accurate structural and stratigraphic models in combination with geo-steering on laterals are key factors in keeping laterals within pay zones during drilling. More than 222 thousand barrels were produced in 2013, which accounts for more than 10% of the state’s total oil production. Determining the economic success of the play awaits longer-term production data, but drilling activity continued to increase in 2014.
In light of the new activity, the Kentucky Geological Survey has begun an 18-month research consortium with industry partners, the Ohio Geological Survey and the U.S. Geological Survey. The consortium will seek to better characterize the Berea horizontal oil play and Berea petroleum system in northeastern Kentucky. Berea oil production in northeastern Kentucky occurs in areas where the source rocks appear to be thermally immature, based on vitrinite reflectance data. In order to better understand the petroleum system, samples of surrounding source rocks are being analyzed for TOC, Rock-Eval pyrolysis and reflectance using vitrinite reflectance and raman spectroscopy along a NW-SE thermal gradient to better evaluate thermal maturity. Also, liquid and gas chromatography-mass spectroscopy of bitumen for biomarker analyses and stable carbon isotope composition will be used from selected oil samples to geochemically tie the produced hydrocarbons to their source. Regional structure and isopach maps are being updated. Numerous cores of the Berea are available at KGS, and excellent Berea outcrops occur updip (west) of the producing area. These will be used to refine reservoir stratigraphy, depositional models, and controls on porosity and permeability.