Hydraulic Stimulation Increases Degasification Rate of Coalbeds

Coal degasification boreholes drilled from the surface have been successfully hydraulically stimulated to increase the flow of gas from the coal. This Bureau of Mines report describes the hydraulic stimulation procedure for a coalbed, the equipment required, and design criteria for the treatment. Three examples of stimulation treatment show from fivefold to twentyfold increases in gas production. The tests were conducted in the Pocahontas No. 3 Coalbed, Buchanan County, Virginia, the Pittsburgh coalbed, Washington County, Pennsylvania, and the Mary Lee coalbed, Jefferson County, Alabama. Two sites where the coal was hydraulically stimulated and exposed by subsequent mining show no adverse effect on mining operations through the treated zones. The induced vertical partings were confined to the coalbed and did not in any way affect either roof or floor rock.