不同煤体结构高阶煤基质的甲烷吸附实验研究

Adsorption experiment of methane in different types of tectonically deformed high-rank coals

为研究不同煤体结构高阶煤基质的甲烷吸附特征,降低在地下开采构造软煤层时,发生煤与瓦斯突出风险;提高构造软煤层煤层气的地面采集效果。文中采用实验研究的方法,对沁水盆地南部寺河矿主采3~#煤层中的构造变形煤进行了分类描述、显微煤岩组分的定量观测、真密度的测定和工业分析,并以甲烷气为吸附质通过等容量法高压吸附实验,分析了不同煤体结构高阶煤基质的吸附特征差异。结果表明：寺河矿高阶煤层变形以脆性变形为主,主要煤体结构可分为原生结构、碎裂结构、碎斑结构、碎粒结构,局部出现碎粉煤;在相同的温度、粒度、吸附平衡压力等条件下,高阶煤基质对甲烷的吸附能力：原状煤〉碎粉煤〉碎裂煤〉碎斑煤〉碎粒煤。即在一定构造破坏范围内,高阶煤基质对甲烷的吸附能力,表现出随构造破坏程度的增加而降低的特征;而当煤体构造破坏超出这一范围,即达碎粉煤阶段后,吸附能力又有所提高,介于原状煤与碎裂煤之间。

Underground coal mining in soft coal seam often suffers from coal and gas outbursts and CBM production in soft coal seam also cannot obtain a satisfactory results. But so far the knowledge about the adsorption capability of methane in high-rank coals is still poor. With No. 3 coal seam of Sihe coalmine in southern Qinshui basin as a study object, tectonically deformed coal samples were classified and de- scribed; coal macerals were quantitatively investigated, true density determination and industry analysis were carried out. And based on above results, methane adsorption experiments were carried out using high pressure volumetric method, analysised the difference of adsorption characteristics in different types of tectonically deformed high-rank coals. The results showed that the mainly coal seam tectonically de- formed of Sihe coalmine is brittle deformation. Coal structure primary texture are original texture, cata- clastic texture, mortar texture , particle structure and a little powder coal. Under the condition of same temperature, particle size and adsorption balance pressure, order of successively adsorption capacity de- creasing is original coal, powder coal, mortar coal, cataclastic coal, speckle coal and granulated coal. As that in a certain range the adsorption capability of methane in high-rank coals reduces with the degree of tectonic deformation increases. But when the coal structure damaged exceeding this range, adsorption ca- pability increase again, always between original, coal and mortar coal.