Mining Publication: Degasification of the Mary Lee Coalbed, Brookwood, Ala
The Bureau of Mines has developed several techniques for draining methane from coalbeds in advance of mining. Drilling long horizontal holes from an underground location is one such technique, which was successfully demonstrated in the Pittsburgh and Sunnyside coalbeds. The same technique has now been applied in the Mary Lee coalbed at Jim Walter Resources, Inc. S No. 4 Mine, Brookwood, Alabama, Where two holes were drilled horizontally--one to a depth of 1,010 feet (308 m) and the other to 540 feet (165 m). The 1,010-foot (308- m) hole proved successful in degasifying a portion of the Mary Lee coalbed. The hole drained methane for 1 year, during which time the initial gas flow of 200,000 ft3/d (5,663 m3/d) declined to 65,000 ft3/d (1,840 m3/d). Total gas production was 40 x 106 ft3 (1.1 X 106 m3). The gas was of commercial quality, with 98 pct methane and a heat rating of 990 btu/ft3 (36.89 Mj/m3). The methane emissions from the faces of the mine section advancing into the degasified zone were reduced by 60 pct. The 540-foot (165-m) hole was terminated prematurely when it became impossible to maintain an open hole. Because of caving, very little gas was drained through this hole.