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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 63 (1979)

Issue: 9. (September)

First Page: 1578

Last Page: 1578

Title: Characterization of Production Mechanism in Devonian Shale and Its Sensitivity to Change in Various Reservoir Parameters: ABSTRACT

Author(s): W. Kent Ford, Harvey S. Price, Kenneth L. Ancell

Article Type: Meeting abstract


The U.S. Department of Energy is supporting cooperative research for enhanced gas recovery in a major effort to help reverse our country's decline in natural gas reserves. A potential major source of natural gas is the Devonian shale of the Appalachian region, estimated to contain hundreds of trillion cubic feet of natural gas. As part of the DOE's Eastern Gas Shales Project, we undertook the task of making a comprehensive analysis of the production of natural gas from the Devonian shales. Two reservoir-stimulation models were validated and used in characterizing the production mechanism of the Devonian shale.

There are two widely held theories on the occurrence of natural gas in the Devonian shales. One theory, the single-porosity theory, is that the gas is present as free gas in a macrofracture system and is produced as Darcy law type flow through these fractures. The second, the dual porosity theory, assumes a macrofracture porosity of smaller magnitude and that, in addition to free gas in the fracture system, there exists a volume of gas present as an adsorbed phase within the shale matrix which diffuses into the fracture system and is produced as pressure drops. The likelihood of one system being present as opposed to the other was studied. Sensitivity analyses were conducted on various reservoir parameters. The validity of conventional transient-pressure-analysis techniques in the Dev nian shale was also investigated.

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