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    邯峰矿区煤储层吸附特性及其控制因素研究

    Study on adsorption characteristics and controlling factors of coal reservoirs in Hanfeng mining area

    • 摘要: 煤对甲烷的吸附能力是决定煤层气储集、运移和产出的关键因素之一,进而影响煤储层的可改造性、生气储气能力和产气效果。以邯峰矿区山西组煤层作为研究对象,系统探讨了煤岩的显微组分、水分与灰分含量以及煤体结构对煤层吸附性能的影响,以期为华北平原煤层气成藏机理和赋存规律提供新的地质认识,同时为太行山东麓地区煤层气的高效开发提供科学支撑。研究结果表明,邯峰矿区煤层气资源丰富,实测含气量一般在8~15 m3/t之间,属于较富甲烷−富甲烷煤层,煤层兰氏体积大但兰氏压力低,具备良好的气体存储能力和低压力下的高效气体吸附能力。随着煤化程度的增加,煤的微孔结构逐渐发育,比表面积增大,从而提高了甲烷的吸附能力。在一定煤化程度范围内,镜质组的增加能为甲烷分子提供更多的吸附位,而惰质组的增加会降低甲烷的吸附能力。水分通过物理占据孔隙空间会减少甲烷吸附的有效位点,灰分通过降低煤体本身的有机质比例而降低煤样的整体吸附能力。当煤体破坏程度越严重时,煤的吸附能力更强。

       

      Abstract: The adsorption capacity of coal to methane is one of the key factors determining the storage, migration and output of coalbed methane, which in turn affects the transformability, gas generation and storage capacity and gas production effect of coal reservoirs. Taking the coal seam of Shanxi Formation in Hanfeng mining area as the research object, the effects of maceral, moisture and ash content of coal rock and coal structure on the adsorption performance of coal seam were systematically discussed, in order to provide a new geological understanding for the accumulation mechanism and occurrence law of coalbed methane in North China Plain, and provide scientific support for the efficient development of coalbed methane in the eastern foot of Taihang Mountain. The results show that the coalbed methane resources in Hanfeng mining area are rich, and the measured gas content is generally between 8~15 m3/t, which belongs to the relatively rich methane-rich coal seam. The coal seam has a large Langmuir volume but low Langmuir pressure, and has good gas storage capacity and high-efficiency gas adsorption capacity under low pressure. With the increase of coalification degree, the micropore structure of coal gradually develops and the specific surface area increases, thus improving the adsorption capacity of methane. In a certain range of coalification degree, the increase of vitrinite can provide more adsorption sites for methane molecules, while the increase of inertinite will reduce the adsorption capacity of methane. Moisture will reduce the effective site of methane adsorption by physically occupying the pore space. Ash will reduce the overall adsorption capacity of coal samples by reducing the proportion of organic matter in the coal body itself. When the degree of coal damage is more serious, the adsorption capacity of coal is stronger.

       

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