Quantitative analysis of methane adsorption/desorption hysteresis effect on coal sample

According to the adsorption/desorption hysteresis phenomenon of the coal samples generally existed, the paper summarized the hysteresis mechanism and analyzed the available quantitative evaluation system and the existed problems. A method was provided to state the desorption hysteresis degree based on the cur ve similar theory. Based on historical experiment data, a correlation analysis on the influence factors was conducted and the hysteresis effect affected to the coalbed m ethane development was revealed. The results showed that a macro methane desorption process essentially was a comprehensive process with the desorption and mig ration two stages and the hysteresis mechanism mainly could reflect the aspects of the desorption resistance and the gas migration resistance. Based on the Frechet di stance features, the curve similarity theory could be applied to state the desorption hysteresis degree. With the temperature increased, the desorption hysteresis degre e would be in a decreased tendency or in a first deceasing and then increasing tendency. The hysteresis degree of the water bearing coal samples would be obviously h igher than the dry coal samples, but there would be no obvious relationship with the water bearing rate. The hysteresis degree of the lump coal sample and pillar coal s ample would be higher than the powder coal sample and the hysteresis degree of the powder coal sample would have no obvious relationship to the coal particle size.