临汾区块煤层气井排采中产出煤粉特征

摘要

基于煤层气井产出煤粉浓度的现场连续监测，采用煤粉浓度监测仪、激光粒度测试仪、反射偏光显微镜、X 射线衍射、电子扫描电镜带 X 射线能谱仪，研究了临汾区块煤层气井排采过程中产出煤粉的浓度、粒度、成分和表面特征，分析了煤粉特征的影响因素，探讨了煤粉产出机理。结果表明，临汾区块平均煤粉浓度随排采阶段的变化趋势是排水降压阶段<憋压排采阶段<气水合采阶段；不同开发层段产出的煤粉浓度变化趋势是单采5号煤<合采5号和8号煤<合采(4+5)号、(8+9)号煤。煤粉颗粒粒径分布范围广，为0.5~1000μm，多集中在100μm以下。煤粉成分以无机矿物和镜质组为主，无机矿物以硬石膏、黄铁矿和伊利石为主。将煤粉颗粒分为光滑表面和粗糙表面两种，光滑表面的煤粉颗粒以C元素为主，粗糙表面的煤粉颗粒以Fe、S、O元素为主。煤粉产出与煤中矿物含量、镜质组含量以及构造煤发育程度和排采阶段有关。%Based on continuous monitoring of pulverized coal concentration of CBM wells, the characteristics of pulver-ized coal during coalbed methane drainage in Linfen block was studied, the factors that influence the characteristics of the pulverized coal were analyzed, and output mechanism of pulverized coal was discussed from the aspect of concentra-tion, particle size, composition and surface characteristics by using pulverized coal concentration monitor, laser particle size analyzer, X-ray diffraction, reflection polarizing microscope, electronic scanning electron microscopy (SEM), X-ray energy dispersive spectrometer. The results show that the trend of average pulverized coal concentration of Linfen block during coalbed methane drainage is drainage depressurizing stage < hold pressure drainage stage < gas hydrate stage, and the trend of different layers is the pulverized coal concentration of single-mined coal seam 5 < that of combined mined coal seam 5, that of coal seam 8 < that of combined mined coal seams 8+9 and 4+5. The particle size distribution of the pulverized coal is wide, ranging from 0.5μm to 1 000μm and most of the particles are concentrated below 100μm. The mineral content of pulverized coal was mainly inorganic mineral and the lens group. The inorganic minerals are mainly hard gypsum, pyrite and illite. The pulverized coal particles were divided into smooth surfaces and rough surfaces. The smooth surfaces of coal particles was composed mainly of element C, and the rough surface of coal particles was mainly composed of elements Fe, S and O. The output of pulverized coal is related to the mineral content of coal, vitrinite con-tent, the development degree of tectonic coal and drainage stage.