不同煤体结构煤的吸附性能及其孔隙结构特征

煤的吸附能力是决定煤层含气量的重要参数。采用沁水盆地东南部赵庄井田二叠系山西组3号煤4个不同煤体结构的高煤阶煤样，通过等温吸附试验分析了不同煤体结构煤样在不同温度和压力下的吸附性能；同时对不同煤体结构煤样进行了低温液氮吸附实验，分析了不同煤体结构煤的孔隙结构特征，从煤体孔隙结构层面分析了不同煤体结构煤的吸附控制机理。结果表明：煤样升压吸附符合Langmuir等温吸附方程，饱和吸附量随煤体破坏程度的增加而增高，随着温度的增高而降低。随着煤体破坏程度的增高，孔容和比表面积也相应增大，孔容主要由中孔贡献，比表面积主要由微孔贡献，糜棱煤的孔容和比表面积在不同孔径阶段均最大，其次为碎粒煤、碎裂煤和原生结构煤；低温液氮吸附实验结果与等温吸附试验反映一致规律，这些说明，在同一地质条件下，煤体结构破坏越严重的地区煤层含气量越高。

Adsorption capacity and its pore structure of coals with different coal body structure

Adsorption capacity of coals is a main reservoir parameter to determine the amount of gas-bearing and exploitive potential in coal seams.To determine the adsorption capacity of coal to methane under different temperatures and pressures related to coal body structures，isothermal adsorption experiments were conducted with four high-rank coal samples of different coal body structures，which were selected from No.3 Shanxi Formation (Permian) coal seam of Zhaozhuang coal mine in south-eastern Qinshui basin.To reveal the control mechanism of porous structure to CBM (coal bed methane) adsorption from microcosmic level，low-temp liquid nitrogen adsorption-desorption experiments on various coal body structure coals were conducted.The results show that coal adsorption to methane is in accordance with Langmuir equation.Saturated adsorption volume increases with the increase of coal deformation degree while decreases with the temperature increase.Pore specific surface area and pore volume increase with the increase of deformation degree in coal body.Wherein，pore volume is mainly dominated by mesopores while pore specific surface area is largely contributed by adsorption pores.Mylonitized coal has the maximum size of pore specific surface area and pore volume under various pore diameters，which is followed by the granulated coal，calaclastic coal and intact coal.The rule concluded is in consistent with that of isothermal adsorption test，indicating that CBM content is higher in area with greater deformed coals under the same geological conditions.