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Liu A.,China University of Mining and Technology | Liu A.,Key Laboratory of CBM Resources and Dynamic Accumulation Process CUMT | Fu X.,China University of Mining and Technology | Fu X.,Xinjiang University | And 5 more authors.
Procedia Engineering | Year: 2011

On the assumption that the rock formations of bending flowage fold is heterogeneous board agglutinated by many isotropic stretch foliums, the paper studied the location of fold neutral surface when the rock formation of fold was under pure buckling only on the basis of elastic thin plate theory, and obtained the location formula of neutral surface of fold with the main parameters of modulus of elasticity, Poisson's ratio, and thickness of each rock formations. Combining Laohe syncline data of Liupanshui coalfield in Guizhou province, the neutral surface of Laohe syncline was located in the fine sandstone of NO.9 coal seam floor of Longtan formation, as far as 966m from the bottom of Maokou formation. The closer coal seam distance from neutral plane, the smaller effect of fold construction on gas occurrence and resulted in less difference between the gas content of coal seam near neutral surface and that of wing of syncline. The research results have certain steering effects on coal bed methane exploitation and preventing coal and gas outburst. © 2011 Published by Elsevier Ltd. Source


Liu A.,China University of Mining and Technology | Liu A.,Key Laboratory of CBM Resources and Dynamic Accumulation Process CUMT | Fu X.,China University of Mining and Technology | Fu X.,Xinjiang University | And 4 more authors.
Fuel | Year: 2013

In low-rank coal (lignite and subbituminous coal) reservoirs, it is difficult to investigate the potential of free and soluble gases at different burial depths because of the lack of measuring methods available in practice. In this work, Mariotte's law was adopted to predict free gas content and methane solubility in coal seam water was studied to calculate soluble gas content. Coal samples were collected from Chinese typical low-rank coal-bearing basins. This study shows volume of pores occupied by free gas becomes smaller when moisture content and confining pressure are high. Methane dissolving tests in four coal seam water samples under set temperatures and pressures show that methane solubility increases with increasing pressure and temperature. Pressure seems to be a more effective influencing factor than temperature on methane solubility although temperature effect is enhanced at high temperature and pressure. A mathematical model of in situ methane content containing adsorbed, free and soluble gases, was established to evaluate the in situ gas content of low-rank coal reservoirs at burial depths from 600 m to 1400 m. While the in situ gas content of the studied coal reservoirs increases with burial depth, the percentage of the free and soluble gases in the in situ contents ranges from 8% to 34%, and hence have to be taken into account in the evaluation of coalbed methane (CBM) potential of low-rank coal reservoirs for CBM recovery. © 2013 Elsevier Ltd. All rights reserved. Source

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