Core of the Month: May 2022

 

Oil from Shale: The KGS-IMMR Mississippian-Devonian Black Shales Cores

Dave Harris, Energy and Minerals Section

 

 

This month we highlight an important collection of research cores gathered in response to global political crises resulting in oil price spikes, the 1973-74 Arab oil embargo, and the 1979 oil crisis.

 

The recent increase in gasoline prices in response to the Russian invasion of Ukraine brings back memories of rationing, long gas lines, price controls, and reduced federal speed limits to improve gas mileage. The 1970s oil shortages spawned new interest in energy efficiency, energy security, and decreasing the United States’ dependence on foreign oil.

 

In Kentucky, this led to new research on the extensive outcrops of Mississippian and Devonian black shales. Organic-rich black shales had been studied as potential sources of synthetic crude oil since the early 1920s (McFarlan, 1943; Barron and others, 1984; Pollock and others, 1981). Kentucky has extensive outcrops of Mississippian and Devonian black shales with organic content of up to 15 percent. These shales have generated hydrocarbons where buried more deeply in the Appalachian and Illinois Basins. Research on the potential to generate commercial oil from the shallow and less thermally mature shales began in 1979 at the Kentucky Center for Energy Research Laboratory (KCERL), managed by the Institute for Mining and Minerals Research (IMMR) at the University of Kentucky (UK).

 

The IMMR oil shale research included topics such as shale oil processing, mine design, resource assessments, and environmental impacts. As part of the resource assessment, 75 shallow core holes were drilled along the horseshoe-shaped black shale outcrop belt from eastern Kentucky across the Cincinnati Arch into west-central Kentucky. In addition, the outcrop belt extending south along the Cumberland Saddle in south-central Kentucky was cored (Fig. 1). Much of this research was presented at the Eastern Oil Shale Symposium held in Lexington annually. These findings and other related papers are published in 13 proceedings volumes from 1981 to 1993, available as PDF files on the KGS website.  

 

The 75 cores from the IMMR research program are housed in the KGS collection at the Earth Analysis Research Library. As part of an ongoing archival project, and thanks to the continued stewardship of the EARL staff, high-resolution box photographs, location information, and related documentation are available online. Links to the archive, funded by the Institute for Museum and Library Sciences (IMLS), are included in the table below.

 

Research on oil shale continued into the early 1990s with funding from the Kentucky Energy Cabinet, U.S. Department of Energy, and various industry partners (Pollock and others, 1981; Barron and others, 1984). In 1988 KCERL was renamed the Center for Applied Energy Research, which conducts a broad range of energy-related research.

Figure 1. Locations of IMMR shallow black shale cores along Devonian outcrop belt in Kentucky.

 

The shale cores collected span the stratigraphic complexities and nomenclature changes from the Mississippian Sunbury Shale and Devonian Ohio Shale in northeastern Kentucky, the Chattanooga Shale in south-central Kentucky, to the New Albany Shale in central and west-central Kentucky. They have provided unweathered continuous stratigraphic sections and rock material for a wide variety of geologic studies over the years. The cores also include partial sections of formations above and below the black shales, including the Borden Group, Fort Payne Formation, Berea Sandstone, Bedford Shale, Boyle Dolomite, Bisher Dolomite, Sellersburg Limestone, Jeffersonville Limestone, and Laurel Dolomite.

 

Downhole gamma-ray and electric logs are available for some of the core holes, and a few cores have core gamma logs made from scintillometer readings. These help to correlate the cores with deeper oil and gas wells.

 

These cores have been used extensively over the years, first in the original oil shale research, and later for a broad range of studies, including:

 

·         Shale oil and shale byproducts

·         Regional stratigraphy

·         Sedimentology and paleoredox studies

·         Thermal maturity and organic geochemistry

·         Trace and rare earth element content

·         University education and industry training, workshops

 

Their significance continues today in ongoing research at KGS to determine the critical mineral content of black shales, especially rare earth elements. Funded by U.S. Geological Survey under their Earth Mapping Resources Initiative (Earth MRI), this 3-year study will focus on mineral resources in central Kentucky, including possible economic levels of trace metals and REE in black shales. Principal investigator for the overall Earth MRI project is Dr. Gina Lukoczki, with Dr. Drew Andrews leading the black shale research. Of particular interest are Devonian phosphate-rich intervals and nodules that are known to have high concentrations of REE in other areas.

 

References

Barron, L.S., Robl, T.L., Kung, J, and Obley, J, 1984, Devonian-Mississippian Oil Shale Resources of Kentucky: A Summary: Proceedings, 1984 Eastern Oil Shale Symposium, University of Kentucky Institute for Mining and Minerals Research, p. 347-363.

 

McFarlan, A.C., 1943, Geology of Kentucky, University of Kentucky, Waverly Press.

 

Pollack, D., Barron, L., and Beard, J, 1981, Stratigraphy and Resource Assessment of the Oil Shales of East Central Kentucky: Proceedings, 1981 Eastern Oil Shale Symposium, University of Kentucky Institute for Mining and Minerals Research, p. 195-212.

 

 

 

Selected core photos from the KGS-IMMR collection:

KGS-IMMR L-17, Marion County, Contact of Miss. Fort Payne

Formation (right) with Dev. Chattanooga Shale (left)

 

 

KGS-IMMR D-3, 134 ft., Bath County. Large pyrite framboid in Ohio Shale. This cropped KGS box core photo illustrates the high resolution of images now available for many KGS cores. Width of core is 2 inches.

KGS-IMMR KEP-2, Lewis County, Contact of Sunbury Shale (right)

and Berea Sandstone (left)

 

KGS-IMMR A-13, Hardin County: Contact of New Albany Shale (right) with Devonian Sellersburg Limestone and Silurian Louisville Limestone.

 

KGS-IMMR black shale core list with links to high resolution core photos