School of Resources and Geosciences, China University of Mining and Technology Key Laboratory of Coalbed Methane Resources and Reservoir Formation Process, Ministry of Education

为了探讨高阶煤孔裂隙连通特征,以沁水盆地南部3号无烟煤层为研究对象,基于煤储层结构三维数字化建模方法,构建了煤层多级次孔裂隙网络结构模型并提取了关键参数,同时结合扫描电子显微镜观测,进一步确认了孔裂隙连通关系以及不同成因类型的孔隙对煤储层连通性的贡献。结果表明:高阶煤孔喉细小,以孔径小于50 nm的中孔为主;孔隙迂曲度较低,截面以方形和正三角形为主,毛管阻力较小;孔隙连通性较差,对连通性起主要作用的是孔径小于50 nm的中孔;差异收缩孔是主要的纳米连通孔隙,该孔隙的发育,形成了具有一定网络拓扑性质的渗流网络结构。孔裂隙网络结构模型表征了孔裂隙分布特征与拓扑关系,能够实现煤岩内部空间的数字化、可视化表征。

In order to have the biogas formation features of the low and medium rank coal, the biogas formation simulation experiments were conducted with Longk ou lignite and Huainan fat coal as the gas maternal sources. Under the same conditions to control other inftluence factors, while seven group experiments were conducte d, the lignite and fat coal samples as the bottom materials were added to the six group experiments individually. With the statistics and analysis on the gas production vo lume and the gas production rate of the biogas, the paper discussed the biogas formation features of the low and medium rank coal. The results showed that in the 90 d ays biogas formation simulation experiments of the coal, the bio-methane gas formation volume and the gas formation rate of the lignite and fat coal experiment groups would have higher gas formation accumulated volume and gas formation rate as the lower of the coal rank generally. The biogas formation of the experiment groups wo uld have three stages generally. The first stage was the rapid uplifting period, the second stage was the stable dropping period and the third stage was tended to the sta ble period. At the first stage, there were differences between the different rank coal samples and the gas generation of Huainan fat coal was early than Longkou lignite. At the early period of the biogas formatted, the methane strains from bios would be the nutrient solution in the culture medium as the main material and the gas formatio n rate would be high. At the late period of the biogas formation, the methane strains from the bios would consume the organic gas in the coal and thus would cause the gas formation rate decreased.

国家自然科学基金资助项目(41330638,41402135,41272154)；江苏省煤基CO2捕集与地质储存重点实验室(中国矿业大学)开放基金资助项目(2015A04)；国家重点基础研究发展计划(973计划)资助项目(2009CB219608)；中石油重大科技专项资助项目(2013E-2205)；