Date of Graduation
The major source of methane influx into deep coal mining operations today is the subsided and broken material behind the active longwall face, the gob, not the coal seam being mined itself. This region is complex and currently beyond the capabilities of traditional reservoir models, as clearly demonstrated by other researchers. An empirically-based approach could provide a useable tool for active mining operations. A complete history and technical background of coalbed methane emissions, methane control technology development, and the differences between international and domestic approaches to the problem is presented to provide the basis for understanding the problem and the need for an empirical approach. Gob gas emissions tend to be fairly consistent in specific operations and regions, so it is possible to create a methane inflow model to forecast such flows once an empirical emission curve can be determined in the field. This work describes such a model, GASMAK, written in FORTRAN and executable on a standard personal computer. The model is very sensitive to the emission input data, as would be expected, but the output is consistent with the limited gob emission data available in the public literature. GASMAK not only forecasts the potential emission from an individual panel, but it also permits the user to divide a longwall panel into individual zones, such as might be serviced by vertical gob wells or cross-measure systems, and assess each individual component as well. This will be a substantial aid to designing efficient and economic methane control systems.
English, Lloyd M., "Gob gas: A synthesis of the literature and an empirical model." (1997). Graduate Theses, Dissertations, and Problem Reports. 8816.