新密煤田裴沟矿主采煤层基质孔隙发育特征

发布时间：2018-02-25 06:04

本文关键词： 裴沟矿二1煤基质孔隙压汞法低温氮气吸附法孔径分布　出处：《河南理工大学》2016年硕士论文　论文类型：学位论文

【摘要】：煤储层中普遍发育孔隙/裂隙,它们对煤层气的吸附、解吸、扩散和运移等过程有着非常重要的影响。煤的组成和不同的沉积埋藏史、构造演化史、煤化作用史、流体活动史和有机质生气史导致煤体内部孔隙/裂隙系统分布不一,尤以与矿井瓦斯突出密切相关的构造煤内部结构更为复杂。以河南省新密煤田裴沟矿主采煤层二1煤为研究对象,应用压汞法和低温氮气吸附法系统分析了全煤层的孔隙的孔容和比表面积的分布特征和变化规律,结果表明:(1)煤层样品的孔容分布介于0.0175-0.0415 ml/g,平均为0.0295 ml/g,从底部到顶部呈水平震荡的“W”形分布,在不同孔径段的分布中多呈多峰型分布;比表面积分布介于0.3010-1.3756 m2/g,平均为0.7305 m2/g,从底部到顶部呈震荡向下的“W”形变化,不同孔径段的分布呈明显的单/双峰分布;平均孔径分布介于77.72-284.47 nm,平均为184.36 nm,从底部到顶部呈震荡增大的趋势,孔隙形态以开放形或半封闭形孔隙为主。(2)相比煤层样品而言,直接顶/底板的孔容、BET比表面积均明显偏大,平均孔径则反之;此外,孔隙形态主要以细颈瓶结构为主;较小孔径段的分形维数要偏小,较大孔径段则偏大。(3)相比低灰分的煤层样品而言,夹矸分层的孔容和平均孔径偏小,BET比表面积偏大,孔隙形貌的差异性却不明显;此外,在较小孔径段,夹矸分层的分形维数要偏小,而较大孔径段则反之。(4)压汞法可以测定5.50 nm-400μm的孔/裂隙,低温氮气吸附法可以测定500 nm以下的较小孔隙,加上假设条件及分析模型等多重因素的作用下导致两种方法在孔容、比表面积及平均孔径等参数出现明显差异;此外,结合分型理论及BJH模型等方法的分析可知压汞法可测煤孔隙的准确下限依据煤质的不同而不同,大致分布集中在80-200 nm之间,低温氮气吸附法的可测上限在100 nm左右。(5)在同一煤层的孔隙发育特征中,构造是控制孔隙发育的主要地质因素,但灰分的影响同样不可忽视,如高岭石和伊利石等无机矿物;但值得注意的是在多种因素的共同作用下,灰分对煤孔隙的影响有可能会复杂化,不同矿物对煤孔隙的相关影响还需要更多的实验去探讨总结。
[Abstract]:Pores / fissures are widely developed in coal reservoirs, which play an important role in the process of coalbed methane adsorption, desorption, diffusion and migration. The composition of coal and different sedimentary burial history, tectonic evolution history, coalification history, etc. Fluid activity history and organic matter generation history lead to different distribution of pore / fissure system in coal body. Especially, the inner structure of tectonic coal, which is closely related to gas outburst, is more complicated. Taking Peigou coal seam 2 1 of Xinmi coalfield in Henan Province as the research object, The distribution and variation of pore volume and specific surface area in coal seams are systematically analyzed by means of mercury injection method and low temperature nitrogen adsorption method. The results show that the pore volume distribution of the sample is between 0.0175-0.0415 ml / g, with an average of 0.0295 ml / g. The distribution of specific surface area is between 0.3010-1.3756 m2 / g, with an average of 0.7305m2 / g. From bottom to top, the distribution of specific surface area is oscillating downward in "W" shape, and the distribution of different pore size shows a single / double peak distribution. The average pore size distribution ranged from 77.72-284.47 nm, with an average of 184.36 nm. The pore morphology of the direct roof / bottom plate was obviously larger than that of the coal seam samples. The average pore size is the opposite; in addition, the pore morphology is dominated by the fine neck bottle structure; the fractal dimension of the smaller pore size segment is smaller, and the larger pore size segment is larger than that of the coal seam sample with low ash content. The pore volume and average pore size of gangue stratification are larger than that of BET, but the difference of pore morphology is not obvious, in addition, the fractal dimension of gangue stratification is smaller in smaller pore size. On the other hand, in the larger pore section, the mercury injection method can be used to determine the pore / fissure at 5.50 nm-400 渭 m, and the low temperature nitrogen adsorption method can determine the smaller pore size below 500nm. In addition, the hypothetical conditions and the analytical model can be used to determine the pore volume of the two methods. In addition, according to the analysis of classification theory and BJH model, it can be seen that the accurate lower limit of mercury injection method for the determination of coal pores is different according to the coal quality, and it is mainly distributed in the range of 80-200 nm. In the pore development characteristics of the same coal seam, the structure is the main geological factor controlling the pore development, but the influence of ash can not be ignored, such as kaolinite and Illite. However, it is worth noting that the influence of ash on coal pores may be complicated under the joint action of many factors, and more experiments are needed to discuss and summarize the related effects of different minerals on coal pores.
【学位授予单位】：河南理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TD84

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