碎裂煤显微裂隙分形结构及其孔渗特征

Fractal structure of microfractures and characteristics of porosity and permeability in cataclastic coals

摘要: 构造煤特有的孔裂隙系统决定了其不同类型具有独特的储层物性,而以脆性变形为主的碎裂煤发育区是煤层气勘探的有利区。根据贵州发耳煤矿9件煤样的显微镜观测和压汞实验数据,分析了构造煤微观变形和显微裂隙分形特征,进而对煤样孔隙渗透特征进行了研究。结果表明:碎裂煤显微裂隙信息维数分布在1.2~1.8;以信息维数为指标,可将碎裂煤划分为3类,信息维数分布范围分别为1.2~1.4、1.4~1.7和1.7~1.8;脆性构造变形增加了孔隙系统中大孔和中孔的孔容,构造变形越强烈,脆性系列构造煤的渗透性能越好。

Abstract: Based on the microscopy and the mercury intrusion tests of 9 coal samples from Faer coal mine in Guizhou Province, we analyzed the characteristics of micro deformation and microfracture in tectonic coal, and conducted research on permeability of pore. Results show that information dimension of microfractures in cataclastic coal ranges at least from 1.2 to 1.8; Based on the index of the information dimension we can classify the cataclastic coals into 3 categories, with their ranges of dimension as follows:1.2~1.4, 1.4~1.7, and 1.7~1.8; As for the pore system, brittle tectonic deformation increased the pore volume of macropore and mesopore. We also find that the greater the tectonic deformation is, the better the permeability of the tectonic coal of brittle series is.