Methane drainage ahead of mining using foam stimulation: Mary Lee Coalbed, Alabama.
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI-PMTC-3(79), 1979 Jan; :1-26
As part of a continuing research effort to determine optimum well design for vertical coalbed gas drainage holes, two test wells were completed into the Mary Lee Coalbed. The wells were foam stimulated and allowed to produce for up to 11 months before being intercepted by mining. Comparatively low water production, prolonged blow-off periods after stimulation, and the wells' ability to produce gas very soon after pumping began, or without pumping at all, indicate that the coalbed in the vicinity of the two test wells was partially draned before completion of each of the wells. Such drained coalbed conditions are considered very suitable for high initial gasflow rates as the two test wells flowed gas at rates from 40 to 180 Mcfd. Underground investigations at or near the test well sites show that fractures induced by stimulation were vertical and were contained in both the coalbed and in the overlying strata. The fractures were found to be longer and much narrower than those induced using heavy gels. A mine gas emission study indicated that the 25 million cubic feet of gas removed may have reduced methane emissions in the vicinity of the two holes as much as 40 percent.
Methane-drainage; Methane-control; Mining-industry; Underground-mining; Coal-mining
IH; Report of Investigations
NTIS Accession No.
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI-PMTC-3(79)