Case Study of the Influence of Longwall Panel Size on Methane Gas Emissions
MCCALL, FRANK E., and FRED GARCIA, U.S. Bureau of Mines, Pittsburgh, PA
The mining of increasingly larger longwall panels has become one of the coal industries primary means of increasing the productivity of its mining operations. Along with the positive productivity aspects of increasing panel size is an expected undesirable increase in gas emissions. A study to document the increase in gas emissions resulting from increasing panel size was conducted by the U.S. Bureau of Mines in the Pocahontas No. 3 coal bed, Virginia, where two contiguous longwall panels were investigated. The first panel was 630 ft wide and the second panel was 700 ft wide. Gas emissions into the mine's ventilation system and gas produced from the gob gas vent holes were monitored during the mining of the two longwall panels. Gas emission data revealed that the second panel produced 9% more total methane gas than the first panel. However, the second panel was only 13% greater in area. Coal and rock core samples were obtained for gas content determination from a hole drilled before mining near the center of the first panel. The gas content data were used to calculate the volume of gas contained in the overburden and underburden strata for comparison to the volume of gas produced during the mining of the two longwall panels. Various geometric shapes were considered for the calculation of the gas volume contained in the strata. The calculations indicated that there must be some lateral migration of methane gas into the region affected by mining.
AAPG Search and Discovery Article #91005 © 1991 Eastern Section Meeting, Pittsburgh, Pennsylvania, September 8-10, 1991 (2009)