By Taylor Kuykendall
\While benefits of the Marcellus shale may spread throughout the state, there is no question the majority of the interest is in the northern counties of West Virginia.
The reason has a lot to do with the topography, or surface of the lands, and the geological makeup beneath. The simplest explanation for the high concentration of Marcellus shale wells in northern West Virginia is that it is more economical to extract gas from there.
Amy Higginbotham of West Virginia University’s Bureau of Business and Economic Research and one of the authors of a study on economic impact of the natural gas industry, said there is Marcellus shale beneath most of West Virginia, but some of it is easier, and therefore cheaper, to reach than the rest.
“There is Marcellus shale under the more mountainous regions in the state,” she said. “But due to the terrain, it makes drilling to the Marcellus shale very difficult.”
A report, “Projecting the Economic Impact of Marcellus Shale Gas Development in West Virginia: A Preliminary Analysis Using Publicly Available Data,” released March 31, 2010, by the National Energy Technology Laboratory described the presence of the Marcellus shale formation beneath West Virginia.
“The Marcellus Shale is present throughout most of West Virginia. It is absent in the southwestern-most counties and also in parts of the eastern-most counties where it also outcrops at surface in some areas,” the report states. “The thickness of the Marcellus varies across the state but is generally thickest in the northeast-central counties and thins to zero in the southwest.”
Thickness is only one measure of the viability of gas production.
“The Marcellus exhibits several different pressure regimes in West Virginia,” the NETL report states. “Generally, it is under-pressured to the southwest and, although there is insufficient data to be certain, it has been postulated to be normal to potentially over-pressured to the northeast with a transitional area in between.”
The varying levels of pressure result in different methods of stimulating wells in preparation for production. Gas foam fracture stimulation is used in the under-pressured and transitional areas, which are generally located in the western half of the state. Over-pressurized areas typically utilize slickwater fracturing methods.
“A minimum depth of drilling for economic production from the Marcellus has yet to be determined in West Virginia,” the report states. “However, according to the West Virginia Geological and Economic Survey, some operators believe that the Marcellus must be greater than 10 feet thick in order to have any appreciable production potential.”
The depth of the Marcellus shale also varies. The shale doesn’t exist in the western reaches of Wayne County and gets progressively deeper as it moves east, until it reaches the Eastern Panhandle, where the shale is either outcropped or nonexistent in some places.
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