--> Abstract: Evaluating Devonian Gas-Shales from the Appalachian Basin, U.S.A, by Ronald Hill, Neil Fishman, George Claypool, Alex Blum, and Denny Eberl; #90078 (2008)

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Evaluating Devonian Gas-Shales from the Appalachian Basin, U.S.A

Ronald Hill1, Neil Fishman2, George Claypool3, Alex Blum4, and Denny Eberl4
1Geology Program, Western State College, Gunnison, CO
2U.S.G.S., Denver, CO
3Consultant, Lakewood, CO
4U.S.G.S., Boulder, CO

Desorbed core gas quantities, kerogen and methane carbon isotopes, total organic carbon (TOC), pyrolysis parameters, and detailed mineralogy were determined for approximately 200 Devonian shale core samples from New York, Virginia, West Virginia, Kentucky, Pennsylvania, and Ohio in the Appalachian Basin. The core samples represent varying levels of thermal maturity, total organic carbon content, mineralogy, and gas content. Total organic carbon content for the shales increases from < 0.1% to more than 10.0%. Although gas content increases with increase in total organic carbon content, thermal maturity, and mineralogy also appear to influence gas content.

Methane carbon isotopes and thermal maturity data provide valuable information for evaluating the type of shale gas resource (indigenous versus migrated) in shale reservoirs. Methane carbon isotope values become less negative as thermal maturity increases. However, in some instances, methane carbon isotope values fall off of the maturity trend, suggesting the shales contain gases that are a mixture of indigenous and migrated gas. By integrating various geochemical techniques, insight into the processes resulting in accumulation of gas in shale reservoirs can be evaluated.

 

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas