随着排采的进行准南东段阜康区块煤层气井产出的煤层气中H2S浓度呈现逐渐增加的趋势，对安全生产构成严重威胁。基于煤层气勘探开发资料，结合实验室厌氧发酵实验，对该区块排采阶段煤层H2S的异常原因进行初步探讨。煤层气勘探阶段含气量测试结果表明，煤层气原始气体中H2S含量低，最高仅为2.152×10−6；排采初期并未出现H2S浓度异常现象，但随着排采的进行，部分井出现异常，如13号井在排采7 a后H2S含量异常增加，高达700×10−6。灰色关联分析表明，H2S的浓度与煤层气井的产水量和水质密切相关，当地下水的补给带来充足的营养物质供给菌群代谢时，就会促进H2S的产出。由该区煤和排采水作为发酵基液构建的厌氧发酵系统表明，H2S的产量与发酵液中SO4 2−含量成反比、与HCO3 −含量成正比；CH4的产气高峰滞后于H2S，且累计生成量显著低于H2S，而由该区的煤与蒸馏水作为发酵基液构建的厌氧发酵系统则以产CH4为主，仅生成微量的H2S，说明H2S是硫酸盐还原菌以CH4为电子供体还原SO4 2−生成的；发酵液中小分子有机酸含量的不断减少说明硫酸盐还原菌同样利用了有机酸为电子供体还原SO4 2−生成H2S。因此，现场生产资料和实验室厌氧发酵结果表明该区H2S是由煤层水中的SO4 2−被硫酸盐还原菌还原生成。这种排采阶段生成的生物气与以往人们认为的原生和次生生物气都不相同，将其称为后生生物气，其中的H2S称为后生生物H2S。排采过程中后生生物气的生成进一步说明人工干预下的煤层气生物工程实施的可行性。

In the Fukang block located in the eastern part of the southern Junggar Basin, coalbed methane (CBM) from CBM wells exhibits a gradually increasing H2S concentration in the process of CBM production via water drainage, severely threatening production safety. Based on the CBM exploration and extraction data, as well as the anaerobic fermentation experiments, this study preliminarily investigated the causes of abnormal H2S concentrations during the CBM production in the Fukang block. As indicated by the gas content test in the CBM exploration stage, the original CBM showed a low H2S concentration of only up to 2.152×10−6. Abnormal H2S concentrations did not occur at the beginning of CBM production. However, some wells exhibited abnormal H2S concentrations as CBM production proceeded. For example, the No.13 CBM well showed an abnormal increase in H2S concentration after seven years of gas production, with the H2S concentration reaching 700×10−6. The grey relational analysis reveals that the H2S concentration is closely related to the yield and quality of water in CBM wells. H2S generation can be promoted under a sufficient supply of nutrients from groundwater for microbial metabolism. As shown by the anaerobic fermentation system constructed with the coal and water produced from the Fukang block as the anaerobic broth, the H2S production was inversely and positively proportional to the SO4 2− and HCO3 − contents in the fermentation broth, respectively. In this system, CH4 showed a lagging gas production peak and significantly lower cumulative gas production compared to H2S. However, the anaerobic fermentation system constructed with coal from the block and distilled water as the fermentation broth primarily produced CH4, with only a small amount of H2S. These findings indicate that H2S was generated from the reduction of SO4 2− by sulfate-reducing bacteria (SRB) using CH4 as electron donors. The gradually decreasing content of low-molecular-weight organic acids in the fermentation broth indicates that SRB also reduced SO4 2− using organic acids as electron donors. Therefore, the field production data and the anaerobic fermentation experimental results indicate that H2S in the Fukang block was generated from the reduction of SO4 2− in the coal seam water by SRB. The biogenic gas generated in the CBM production stage, which is different from primary and secondary biogenic gases, is referred to as the epigenetic biogenic gas, in which the H2S is called epigenetic biogenic H2S. The generation of epigenetic biogenic gas during the CBM production further corroborates the feasibility of implementing CBM bioengineering under human intervention.