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近年的煤层气勘探开发工作中，主要从热成气角度考虑煤层甲烷的气源，而煤能否被厌氧菌降解生成次生生物气则一直是人们所关心的问题。采用“悬浮接种物”作为接种源，对山西柳林庙湾矿石炭、二叠系的两个煤样进行了不同温阶下的生物降解产气模拟实验。实验表明：温度超过７５℃停止产气；所产气体为甲烷和二氧化碳，其中甲烷具有轻碳同位素值的特征，δ１３Ｃ１为－４９．１６‰，从气体组成和δ１３Ｃ１值来看，模拟实验所产气体属生物气。结果认为，煤可以被厌氧生物降解生成次生生物气；这种二次成气或叠加成气作用可以增加浅煤层中煤层甲烷的绝对含量，相应提高煤层甲烷的勘探成功率；厌氧环境的存在从另一个侧面也反映煤层甲烷的保存条件较好；存在煤层二次生物气是寻找煤层甲烷气藏的一个标志。

COAL GAS GENERATION BY ANAEROBIC DEGRADATION

??In coal-bed gas exploration and development in recent years, the gas source of the coal-bed methane is mainly considered from the viewpoint of thermogenic gas, however, whether the secondary biogas can be generated through the degradation of coal by anaerobic bacteria is always a problem concerned by the people.By use of the "Suspended inocula"as the inoculating source, an analog experiment on gas generation by biodegradation at different temperature ranks was carried out for two coal samples from the Carboniferous-Permian in the Miaowan coal mine, Liulin, Shanxi.It is shown by the experiment that when the temperature exceeds 75??, gas generation is stopped;the gas generated is methane and carbon dioxide and the methane has the property of light carbon isotope;the ??¹³C₁ is -49.16??;and according to the gas composition and ??¹³C₁ value, the gas generated by the analog experiment belongs to biogas.It is concluded that the coal can be degraded into secondary biogas by anaerobic organism;the absolute content of coal-bed methane in the shallow coal-bed can be increased by secondary or superposition gas generation, thus raising the success ratio of exploration for coal-bed methane;the existence of anaerobic environment reflects that the preservation condition of coal-bed methane is good from other side;and the existence of secondary biogas in coal-bed is a sign of surveying the coal-bed methane reservoir.