山西省煤层气(瓦斯)开发利用现状及发展方向

为了探究煤岩体系微观组分及孔隙结构对甲烷吸附的影响规律, 选取沙曲一矿6组煤岩样, 通过工业分析、X射线衍射、扫描电镜与能谱分析、低温氮吸附、计算机断层扫描, 以及煤岩甲烷吸附实验，分别研究煤岩样微观组分、孔隙结构特征对甲烷吸附的影响。研究结果表明: 煤样和岩样无机组分质量分数分别为15.82%~20.93%、90.80%~94.68%, 均以石英和黏土矿物为主；岩样BET比表面积为3.32~8.70 m²/g、吸附孔体积为0.009 5~0.019 1 cm³/g, 均大于煤样的BET比表面积和吸附孔体积；岩样孔隙表面粗糙度、孔结构复杂度略大于煤样的孔隙表面粗糙度、孔结构复杂度, 与黏土矿物含量高有关。煤岩样甲烷等温吸附曲线均符合朗格缪尔模型, 可用极限吸附量V_L和朗格缪尔压力p_L描述吸附规律；相同吸附温度下, 岩样存在一定的吸附性, 煤样吸附性远大于岩样。分析得出, 煤岩样的有机组分含量、黏土矿物含量、表面分形维数、比表面积和吸附孔体积对甲烷吸附过程V_L、p_L影响显著。基于多元线性回归分析了5种因素对甲烷吸附规律的影响关系: 有机组分含量高、比表面积大的样品CH₄分子极限吸附量V_L越大, 而黏土矿物含量高不利于吸附甲烷；吸附孔体积越小、黏土矿物含量越高、比表面积越大, 朗格缪尔压力p_L越大。

Present situation and development direction of coalbed methane (gas) exploitationand utilization in Shanxi Province

In order to explore the influence of the micro-components and pore structure of the coal-rock system on methane adsorption, six groups of coal samples of Shaqu No.1 mine were selected to study the effects of microscopic components and pore structure characteristics on methane adsorption by industrial analysis, X-ray diffraction, scanning electron microscopy and energy spectrum analysis, low-temperature nitrogen adsorption, computed tomography and coal-rock methane adsorption experiments.The research results show that the content of inorganic components in coal samples is 15.82% to 20.93%, and that in rock samples is 90.80% to 94.68%, which are mainly composed of quartz and clay minerals.The BET specific surface area of the rock sample is 3.32 m²/g to 8.70 m²/g and the adsorption pore volume is 0.009 5 cm³/g to 0.019 1 cm³/g, which are all larger than those of the coal sample.The pore surface roughness and pore structure complexity of the rock sample are slightly larger than those of the coal sample, which are related to the high content of clay minerals.The methane adsorption isotherm curves of coal-rock samples are all in line with the Langmuir model, and the adsorption law can be described by the limit adsorption capacity V_L and Langmuir pressure p_L; under the same adsorption temperature, the adsorption property of coal samples is much larger than that of rock samples, and there is a certain adsorption of rock samples.The analysis shows that the content of organic components, clay mineral content, surface fractal dimension, specific surface area and adsorption pore volume have significant effects on the V_L and p_L of the methane adsorption process.Based on multiple linear regression, the influence of 5 factors on methane adsorption was analyzed.The sample with high content of organic components and large specific surface area of CH₄ molecule has a larger limit adsorption capacity V_L, while high content of clay minerals is not conducive to the adsorption of methane; the smaller the adsorption pore volume, the higher the content of clay minerals, the larger the specific surface area and the greater the Langmuir pressure p_L is.