【摘要】 扬子地台下寒武统发育一套富有机质泥页岩,是中国页岩气勘探开发的重点层位之一。通过扫描电镜、低温氮气吸附和高压CH4吸附实验对遵义牛蹄塘组、南京幕府山组和池州黄柏岭组3套同一层系的下寒武统页岩微观孔隙和CH4吸附特征进行分析,并结合有机质特征、矿物组成等研究页岩孔隙及含气性能的影响因素,结果表明:(1)下寒武统页岩微观孔隙类型众多,以有机孔、黏土矿物层间孔和微裂缝为主,亦含有一定量的矿物晶间孔、黄铁矿溶蚀脱落后形成的蜂窝状孔隙以及溶蚀印模等;(2)DFT孔径分布显示下寒武统页岩和干酪根以小于4nm孔隙为主,页岩中同时含有一定量的4nm以上的孔隙,可能是来自蒙脱石;(3)所研究的下寒武统页岩比表面积、孔体积和Langmuir CH4吸附容量分别为5.58~31.96m2/g、0.026~0.088m L/g和1.36~5.3m L/g,总体上受控于有机碳含量和蒙脱石含量,但TOC和蒙脱石对不同地区下寒武统页岩物性和含气性的影响具有明显分异的现象;(4)2个牛蹄塘组干酪根的比表面积是其页岩的7.08和7.92倍,CH4吸附容量是其页岩的5.81和7.09倍,显示出干酪根是CH4吸附气赋存的主要载体之一。更多还原

【Abstract】 The lower Cambrian develops a set of organic-rich black shales in Yangtze Platform and is regarded as one of the key layers of shale gas exploration. The microscope pore structure characteristics and methane sorption capacity were investigated using scanning electron microscope,nitrogen adsorption and methane sorption experiments,and then their controlling factors combining with organic matter,mineral compositions were discussed for Niutitang shales in Zunyi area,Mufushan shales in Nanjing area and Huangboling shales in Chizhou area. The results show as below:( 1) The pores in lower Cambrian shales are mainly dominated by organic pores,interlayer pores in clay minerals and micro-fractures,as well as containing some intergranular pores between brittle mineral grains,honeycomb pores formed by pyrite crystals falling out,and dissolution molds in fossils;( 2) DFT pore size distributions show the pores is mainly concentrated in the range of less than 4nm in lower Cambrian shales and kerogens,while a certain amount of pores are above 4nm are also existed in lower Cambrian shales,which may be contributed by smectite;( 3) The specific surface area,pore volume and Langmuir methane sorption capacity of the lower Cambrian shales are ranging from 5. 58 to 31. 96m2/ g,0. 026 to0. 088m L / g and 1. 36 to 5. 3m L / g,respectively,which are mainly controlled by TOC and smectite contents,but the effect of TOC and smectite on physical properties are quite different for the lower Cambrian shales in different regions;( 4) The specific surface area of two Niutitang kerogens are 7. 08 and 7. 92 times than that of the shales and methane sorption capacity of kerogens are 5. 81 and 7. 09 times than that of the shales,suggesting that kerogen is a main carrier of methane gas occurrence in.更多还原