Unconventional gas wells are being drilled through coal reserves in Pennsylvania, West Virginia, and Ohio. The ability for both mining and gas producing activities to coexist safely is a continuing question for federal and state regulatory entities and for industry representatives. A hypothetical, gas well casing failure resulting from mining-induced ground movements could produce unsafe conditions in nearby operating mines and an explosion hazard. NIOSH is conducting research to characterize a hypothetical breach from an unconventional gas well and any resulting mine safety consequences for a range of mining conditions. These conditions include overburden depths of under 152 m (500 ft), between 152 (500 ft) and 274 m (900 ft) and over 274 m (900 ft). Multiple technical approaches are utilized to address the research questions. NIOSH is providing scientific input to our partners in the development of new guidelines for shale gas wells influenced by longwall mining. A summary of the current findings across all tasks is provided. The shallow cover site showed a one to two orders of magnitude increase in maximum permeability compared to the deep cover site. Stream valley conditions tended to retain much the maximum achieved permeability after mine by, up to 90%.
