耦合理论模型与数值模拟方法,详细分析了煤储层孔隙结构分形特征对煤层气运移的控制作用.首先,采用Menger海绵体构造思想模拟了三维煤岩介质的非线性孔隙结构;随后,借助多孔介质渗透率的串联,并联模式预测模型,推导出分形多孔介质渗透率同孔径分布特征之间的关系,并采用格子波尔兹曼方法验证了其有效性.基于耦合方法,系统分析了分形多孔介质孔隙度,孔隙结构分形维数Db,孔径范围[rmin,rmax]等参数对其渗透率的影响,结果表明:①最大孔径rmax形成的通道主宰,呈近2次方关系;②最大孔径同最小孔径比越大,渗透率越高;③Db与之间呈负幂乘关系,并表现出分段特征,拐点为Db=2.5附近.综合以上分析结果,推演出分形多孔介质渗透率预测模型为max n Cfr,其中C为常量,n为接近2的常量,f是同孔隙结构信息相关的表达式.最后,本文还讨论了Db=2时,本文预测模型与Kozeny和Carman模型=Crn的等效性.
As a new technology, Atomil Force Microscopy （AFM） is being used in the research of microscopic structure on coal surface in recent years. By this technology, we can observe the nanoscale pore and crack shape of coal surface, and measure some structural parameters. Different metamorphic grades produce different feature of surface microscopic structure of coal. This paper analyzes the surface microscopic structure of different metamorphic grade coal by AFM. The results show that the coal surface microstructure has a trend from rough to smooth with the increasing of metamorphic grade. The low rank coals contain large or medium pores and the high rank coals contain micro pores. The values of surface morphology characteristic parameters （Sq and Sa） nonlinearly decrease with the increasing coal rank. That is, the coal surface becomes smoother during coalification.
Jie-Nan PAN Hai-Tao ZHU He-Ling BAI Yan-Qing ZHAO Hai-Chao WANG Li-Ping YAO
