柳林区块煤层气水平井煤粉产出特征及影响因素研究

Study on CBM Horizontal Well Coal Fines Generation Features and Impacting Factors in Liulin Block

为了揭示煤层气水平井产出煤粉特征,开展了柳林区块L1煤层气水平井产出煤粉的现场连续监测,采用精密天平、激光粒度测试仪和扫描电镜对煤粉样品进行浓度测量、粒度测试和形态观察。分析了煤层气水平井在排采过程中产出煤粉的浓度、粒度和形态特征及其影响因素。结果表明,煤粉浓度范围为0.2~6.5 g/L,煤层气井排采参数的突然改变会使煤储层受到气液流的冲蚀,导致煤粉浓度的增加;煤粉颗粒分布范围为1~500μm,煤粉粒度的大小与气液流速有关,排采参数发生变化,气液流速增大会将粒度较大的煤粉带到井口;煤粉颗粒的形态主要为块状和粒状,煤粉颗粒的形态与煤层的煤体结构类型有关,煤粉颗粒有光滑表面和粗糙表面两种,表面常附着有高岭石等无机矿物,煤粉表面特征与煤岩和无机矿物成分有关。

To reveal CBM horizontal well coal fines generation features has carried out continuous site monitoring on coal fines generation in CBM horizontal well L1 of Liulin block.Using precision balance,laser particle sizer and scanning electron microscope have carried out coal fines sample concentration measurement,particle size analysis and morphological observation;also analyzed CBM horizontal well generated coal fines concentration,particle size and morphological features as well as impacting factors.The results have shown that coal fines concentration range is 0.2~6.5g/L,CBM well drainage parameters abrupt varying will cause coal fines concentration increasing as a result of coal reservoir gas and liquid scouring.Coal fines particle size distribution range is 1~500μm,the size is related to gas and liquid flow rate,drainage parameters varied,gas and liquid flow rate increasing will bring larger sized coal fines to wellhead.Coal fines particle morphology is mainly blocky and granular,the morphology is related to coal mass structural type;particles have smooth and coarse two types often adhered with kaolinite etc inorganic minerals on surfaces;thus coal fines surface features are related to coal petrological and inorganic mineral components.