These observed shows were commonly large enough to force cable drilling tools up the wellbore.
Based on a review of these older wells, it is surprising that interest in this play failed to occur sooner as the shows were consistent, repeatable, and present over a large geographic area.
The Marcellus Shale tests drilled in 1982 in Washington County, Pennsylvania, are located adjacent to the Range Resources initial Renz discovery well and core development area for the Marcellus Shale.
In Allegheny and Washington counties of Pennsylvania, two of the four attempted tests of the Marcellus were completed with carbon dioxide or nitrogen foam treatments and showed the poorest results of these early tests.
These studies led the way to a significant expansion of the Big Sandy field into southwestern and central West Virginia and parts of southeastern Ohio.
A large segment of the EGSP can be accessed from the National Energy Technology Laboratory.
The wide area of prospective acreage, favorable geologic setting, and early production flow-test rates all suggest that the Marcellus Shale play contains enormous reserve potential, establishing the Marcellus Shale play as one of the major hydrocarbon accumulations in the world. A total of 595 separate reports, articles, and reviews were generated by researchers working under the EGSP, leading to a voluminous available database on all the eastern shales, including the Marcellus Shale.
In the Appalachian Basin, this enormous research effort was mostly directed toward the study of the controls on production within the Big Sandy field and to identify new major areas of Devonian shale-gas potential.
The play has attracted the attention of independents, major oil companies, and international partners, as discoveries continue to expand the scope of the play and shed light on the formation's reservoir characteristics and economic potential.
To date, a total of more than 21,000 wells have been drilled in the Big Sandy field in eastern Kentucky, southern West Virginia, southern Ohio, and southwestern Virginia.
The primary target in the Big Sandy field is the Upper Devonian Huron Shale, with contributions from the Cleveland, Rhinestreet, and Marcellus Shale intervals.
These shallow wells were used mainly for domestic and light industrial purposes and were extensively developed from the 1860s through the mid-1900s.
The first major shale discovery in the Appalachian Basin was in 1921 in northeastern Kentucky, which established the Big Sandy field.