An analysis of reservoir conditions and responses in longwall panel overburden during mining and its effect on gob gas well performance

摘要: Abstract NIOSH conducted a cooperative research study to provide direct measurements of changing reservoir conditions in longwall panel overburden. The field documented changes permeabilities, methane concentrations, fluid pressures, and the effects adjacent gob gas ventholes (GGVs) on boreholes drilled panel. Three different stratigraphic horizons were monitored by boreholes. Results indicated that venthole fracture network formed 24 46 m (80 150 ft) ahead mining face. Overburden permeabilities within same overburden test zones ~ 1 md prior undermining, increasing hundreds or thousands md during undermining. Permeabilities measured seven months after undermining showed additional increases. relationship between conditions, face position, surface movement is discussed. Recommendations are made optimize GGV performance evaluating subsidence produced mining, resulting rock stresses substantially influence induced permeability. Mechanisms account for observed reported.