基于热力学模型的煤孔隙结构分形表征

Fractal characterization of pore structure in coals based on thermodynamics model

煤的孔隙结构复杂,难以用传统的欧氏几何理论描述其复杂性,而分形理论可定量表征孔隙结构的复杂程度。通过对渭北煤田韩城矿区10个煤样进行的压汞实验,采用热力学分形模型,获得了煤的渗流孔的分形维数,定量表征了煤的孔隙特征,并探讨了分形维数与渗透率的关系。研究表明:对于同等变质程度的煤来说,煤中吸附孔越多,孔隙分形维数越大;煤孔隙分形维数与渗透性呈负相关关系。由此可见,煤的渗流孔分形维数可作为煤储层渗透性评价的定量指标之一。

The pore structure of coal is complex and it is difficult to characterize pore structure by traditionalEuclidean geometry. However, fractal theory is an effective method to investigate the irregularities of porestructure. The fractal dimensions of seepage-pores of 10 coal samples collected from Hancheng mining area inWeibei coalfield were obtained using mercury injection experiment based upon thermodynamic fractal model andthe geometric properties of pore were quantitatively characterized. The relationship between fractal dimension andpermeability was also discussed. The results show that the more adsorption-pores, the higher fractal dimension forthe same coal rank. The fractal dimension has a negative correlation with the petrologic permeability of coal. Thefractal dimension of seepage-pores of coals can be used as one of the quantitative indexes for evaluation ofpermeability of coal reservoir.