煤层气生物工程技术是实现富油煤绿色、低碳开发的有效手段之一。 为探究微生物厌氧发 酵作用下富油煤孔隙结构演化特征,以鄂尔多斯盆地南部黄陵矿区富油煤为研究对象,在实验室条 件下开展微生物厌氧发酵(降解)富油煤生烃模拟实验,采用场发射扫描电镜、3D 形貌仪、CT 扫 描、孔隙度 / 渗透率测试等手段,对微生物降解前后的富油煤表面形貌、粗糙度和内部孔隙进行表 征,并探讨微生物降解作用下富油煤的孔渗结构演化规律及生烃机制。 结果表明:不同规格大小的 煤样甲烷生成潜力与煤的质量( 或接触面积) 呈正相关关系;微生物降解作用具有显著的扩孔、增 孔、增容、造缝等效果,以及降低煤体表面粗糙度,使其变得平滑,有利于煤层气的解吸和运移;微生 物还可沿着节理、裂隙系统进入富油煤内部,改造煤体孔隙结构及其连通性;同时微生物降解作用 还可提高富油煤的孔隙度和渗透率,为煤层气的渗流和运移提供了良好的通道。 微生物主要作用 于富油煤中脂肪族上的支链,打破小分子间连接较弱的氢键,降低脂肪族的分支程度和煤结构的交 联度,进而生成甲烷。 微生物作用还可改变富油煤芳香度和芳香环的缩合程度,进而改变富油煤大 分子结构与孔隙结构。 微生物厌氧发酵富油煤与非富油煤的生烃机制差异性问题值得后续深入 研究。

Coalbed gas bioengineering technology is one of the effective means to achieve a green and low-carbon de- velopment of tar-rich coal. To explore the pore structure evolution characteristics of tar-rich coal during the process of biodegradation,tar-rich coal samples from the Huangling mining area in the southern Ordos Basin were investigated. The simulation experiment of anaerobic fermentation or biodegradation of coal and hydrocarbon generation was carried out under laboratory conditions. The surface morphology,roughness,and internal pore space of tar-rich coal before- and after-biodegradation were characterized utilizing field emission scanning electron microscopy (FE-SEM),three-dimensional (3D)morphometry,computer tomography (CT)scanning,and porosity/permeability test. The evolution law of tar-rich coal reservoir pore structure under biodegradation and the enlightenment of geological development were al- so discussed. The results show that the methane yield with different sizes is positively correlated with the coal quality or contact area between microbe and coal. Biodegradation has some significant effects on pore expansion,pore in- crease,volume increase,and fracture formation,as well as reducing the surface roughness of the coal body and making it smooth,which is beneficial to the desorption and transport of coalbed methane. Microorganisms can also enter the in- terior of tar-rich coal along the joints and fracture system to modify the pore structure of the coal body and its connec- tivity. At the same time,biodegradation can also increase the porosity and permeability of tar-rich coal reservoirs,pro- viding a good channel for coalbed methane seepage and transport. Microorganisms mainly act on the branched chains on the aliphatic groups in the coal to break the weakly connected hydrogen bonds between small molecules, reduce the degree of branching of the aliphatic groups and the degree of cross-linking of the coal structure,and then produce methane. Biodegradation can also break the bonds connected between the aromatic layers of tar-rich coals,in- crease the web spacing, change the aromaticity and the degree of condensation of aromatic rings, and thus change the molecular and pore structures of coal. The difference in methane generation mechanism between tar- rich coal and non-tar-rich coal in microbial anaerobic fermentation is worthy of further study.