Fossil Fuels Petroleum

ANALYSIS OF DEVONIAN BLACK SHALES IN KENTUCKY FOR POTENTIAL CARBON DIOXIDE SEQUESTRATION AND ENHANCED NATURAL GAS PRODUCTION

Authors: Brandon C. Nuttall
 
Abstract: Devonian gas shales underlie approximately two-thirds of Kentucky. In the shale, natural gas is adsorbed on clay and kerogen surfaces. This is analogous to methane storage in coal beds, where CO2 is preferentially adsorbed, displacing methane. Black shales may similarly desorb methane in the presence of CO2. Drill cuttings from the Kentucky Geological Survey Well Sample and Core Library were sampled to determine CO2 and CH4 adsorption isotherms. Sidewall core samples were acquired to investigate CO2 displacement of methane. An elemental capture spectroscopy log was acquired to investigate possible correlations between adsorption capacity and mineralogy. Average random vitrinite reflectance data range from 0.78 to 1.59 (upper oil to wet gas and condensate hydrocarbon maturity range). Total organic content determined from acid-washed samples ranges from 0.69 to 14 percent. CO2 adsorption capacities at 400 psi range from a low of 14 scf/ton in less organic-rich zones to more than 136 scf/ton. There is a direct correlation between measured total organic carbon content and the adsorptive capacity of the shale; CO2 adsorption capacity increases with increasing organic carbon content. Initial estimates based on these data indicate a sequestration capacity of 5.3 billion tons of CO2 in the Lower Huron Member of the Ohio Shale of eastern Kentucky and as much as 28 billion tons total in the deeper and thicker parts of the Devonian shales in Kentucky. Should the black shales of Kentucky prove to be a viable geologic sink for CO2, their extensive occurrence in Paleozoic basins across North America would make them an attractive regional target for economic CO2 storage and enhanced natural gas production.
Publication Date: 28 Jan 2005
DOE Contract number: FC26-02NT41442
Resource Type: Technical Report
Resource Relation: Other Information: PBD: 28 Jan 2005
Research Organizations: University of Kentucky (US)
Sponsoring Organizations: (US)
Country of Publication: United States
Language: English
Keywords relating to this report:
ADSORPTION ISOTHERMS
BLACK SHALES
CARBON
CARBON DIOXIDE
GEOLOGIC SURVEYS
HYDROCARBONS
KEROGEN
METHANE
MINERALOGY
NATURAL GAS
SHALES
SPECTROSCOPY
STORAGE
VITRINITE

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