Study On Characteristics Of Adsorption/Desorption Of Medium And High Rank Tectonically Deformed Coals In Henan Province

The methane adsorption/desorption capacity and characteristics were related to the degree of coal metamorphism and deformation structure.The macro-microcosmic structure observation,SEM,Ro test,maceral determination,LND and isothermal adsorption/desorption experiment of medium and high rank tectonically deformed coals samples at typical miningfields in Henan Province were conducted.Combined previous research results of tectonically deformed coal,the adsorption/desorption characteristics of medium and high rank tectonically deformed coals was analyzed from the perspective of nanoscale pore.The influence of metamorphism and deformation on nanoscale pore structure and methane adsorption/desorption characteristics were analyzed and discussed.Results show that the pore volume and the surface area are respectively controlled by transitional pores(10 to 100 nm) and micropores(1.5 to 10nm).Entrance of coal sample with strong tectonic deformation of relevance, entrance overall increases with tectonic deformation degree of enhancement.The coals pore has obvious fractal characters,the comprehensive fractal dimension of coal samples with entrance, specific surface area increases.The methane adsorption capacity of weak brittle tectonically deformed coals of medium and high rank increased with increasing along with the degree of coal metamorphism. As the pressure rised,the increment of methane absorption quantity decreased gradually and tended to zero,while the increment of methane absorption quantity increased with the increment of the degree of coal metamorphism. The methane desorption quantity during unit pressure within the period increased with power function with the pressure decreasing. With the degree of coal metamorphism increased,the methane desorption quantity during unit pressure within the period increased. The methane desorption quantity curve was monotone increasing logarithmic function with pressure decreased to different tectonically deformed coals,the methane desorption quantity was improved with the increasing tectonic deformation degree.The relationship of Langmuir volume content with nanoscale pore entrance and the surface area of medium and high rank tectonically deformed coals was of linear regression;the methane adsorption capacity of medium and high rank tectonically deformed coals increased with increasing along with the fractal dimension.The distribution relationship of transitional pores and micropores has important influence on the coalbed methane desorption characteristics,and the biger the transitional pores volume, the easier the methane desorption.