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Mining Contract: The Role of Gas Desorption in the Energetic Failure of Coal

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Contract #200-2008-25702
Start Date6/26/2008
End Date7/31/2012
Research Concept

This research will conduct laboratory experiments on coal samples collected from at least three operating coal mines. These samples will be loaded to simulate original confinement conditions and will include a sorbed gas condition. Loading will cover a range of conditions, and measurements will include gas desorption rates, permeability evolution, deformation, and acoustic emissions. These data will be used to define modes of failures including the role of a desorbing gas phase on the energetic failure of coal.

Topic Area

Contract Status & Impact

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Gas transport in coal seams is different from that of other rock types because of gas sorption and coal swelling. The relative roles of stress level, gas pressure, gas composition, fracture geometry of coal, and water content are directly connected to the processes of gas sorption, diffusion, transport, and coal swelling. Although scientific research on coal-gas interactions has been conducted for more than a century, the physicochemical and hydro-thermodynamic phenomena are still not fully understood. Understanding and quantifying these interactions is essential in developing the best possible process-based models of behavior that incorporate key observed responses.

This contract explored the role of gas desorption on the energetic failure of coal in coal mine bumps and bursts. The contractor developed and used experimental methods to measure the mechanical and transport properties of coal under in situ geophysical and geochemical conditions. These methods included measurement of the deformation response and evolution of permeability and sorption capacity under variable paths of stress and gas pressure and composition. Critical characterizations include the evolution of permeability, sorption/desorption characteristics, and the strength of fractured and intact coals under varied stress paths. These observations were then applied to mechanistic models to understand response, in situ. Results provided new fundamental insights into coal gas desorption and energetic failure of coal. These results will support future applied work on reducing accidents involving bumps and bursts.