摘要
To promote gas extraction in low-rank high-gas coal beds, the pore structure characteristics of the coal and their effect on gas desorption were studied. The results show that micropores are relatively rare in low-rank coal; mesopores are usually semi-open and inkpot-shaped whereas macropores are usually slit-shaped. Gas desorption is relatively easy at high- pressure stages, whereas it is difficult at low-pressure stages because of the 'bottleneck effect' of the semi-open inkpot-shaped mesopores. A 'two-three-two' gas extraction model was established following experimental analysis and engineering practice applied in the Binchang mining area. In this model, gas extraction is divided into three periods: a planning period, a transitional period and a production period. In each period, surface extraction and underground extraction are performed simultaneously, and pressure-relief extraction and conventional extraction are coupled to each other. After applying this model, the gas extraction rate rose to 78.8 %.
基金
Acknowledgments The research was supported by the National Basic Research Programme of China (973 Project) (2011CB201205), National Natural Science Foundation of China (51474211), and the National Key Technology R&D Program (2012BAK04B07).