AAPG Annual Convention and Exhibition

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Evaluation of Geological Characteristics of the New Albany Shale as a Potential Liquids-From-Shale Play in the Illinois Basin


The New Albany Shale in the Illinois Basin is a Middle and Upper Devonian to Lower Mississippian unit correlative with the Antrim Shale of the Michigan Basin and the Ohio and Marcellus Shales of the Appalachian Basin. These shale units are thought to be part of a succession deposited in response to a sea-level rise over large areas of the North American craton, and they are important targets for recent unconventional gas and oil shale developments. The New Albany Shale has been a producer of natural gas in Indiana and Kentucky for more than 150 years, and numerous studies have attempted to understand factors that control gas distribution and producibility within the unit. Even though it has been long known that most of the conventional oil found in the Illinois Basin was sourced from the New Albany Shale, little is known about the volume and distribution of liquid hydrocarbons that currently exist within this formation. Commercial and academic interest in in-situ liquid hydrocarbons in the New Albany Shale arose only recently owing to the possibility of producing oil via horizontal drilling and hydraulic fracturing. The available data on organic matter maturity of the New Albany Shale indicate that significant areas in Illinois and some in Indiana and Kentucky lie within the oil window at suitable depths and may have sealing units in place to preserve generated hydrocarbon liquids. Abundant organic matter of marine origin provides an excellent source for hydrocarbons. The presence of oil in the New Albany Shale is confirmed by oil shows, and core analyses. Finally, recent production of oil from the unit in Kentucky clearly confirms the presence of in-situ liquids. Yet, the exact amounts of in-situ hydrocarbons are unknown, and former estimates of the near absence of oil in the New Albany Shale were based on a dearth of relevant data that hindered rigorous evaluation. This presentation re-examines geological and reservoir properties of the New Albany Shale as a potential liquids-from-shale play in the Illinois basin. In addition to the previously available data, new data from recent exploratory wells in Indiana and production wells in Kentucky on organic petrology and geochemistry will be discussed to understand the hydrocarbon generative potential and quality of the generated hydrocarbons.