Relationship between nano-scale defo

Relationship between nano-scale deformation of coal structure and metamorphic-deformed environments

There is a more consanguineous relation between nano-scale deformation of coal structure and metamorphic-deformed environment. In different metamorphic-deformed environments, deformation in the coal structure can occur not only at micro-scale, but also at nano-scale, and even leads to the change of molecular structure and nano-scale pore (<100 nm) structure. The latter is the main space absorbing coalbed methane. Through X-ray diffraction (XRD) and liquid-nitrogen absorption methods, the characteristics of macromolecular and nano-scale pore structures of coals in different metamorphic-deformed environments and deformational series of coals have been studied. By combining with high-resolution transmission electron microcopy (HRTEM), the macromolecular and nano-scale pore structures are also directly observed. These results demonstrate that the stacking Lc of the macromolecular BSU in tectonic coals increases quickly from the metamorphic-deformed environment of low rank coals to that of high rank coals. For different deformed tectonic coals, in the same metamorphic-deformed environment, the difference of Lc is obvious. These changes reflect chiefly the difference of different temperature and stress effect of nano-scale deformation in tectonic coals. The factor of temperature plays a greater role in the increase of macromolecular structure parameters Lc, the influence of stress factor is also important. With the stress strengthening, Lc shows an increasing trend, and La /Lc shows a decreasing trend. Therefore, Lc and La /Lc can be used as the indicator of nano-scale deformation degree of tectonic coals. With increasing temperature and pressure, especially oriented stress, the orientation of molecular structure becomes stronger, and ordering degree of C-nets and the arrangement of BSU are obviously enhanced. For the deformation of nano-scale pore structure, in the same metamorphic-deformed environment, along with the strengthening of stress, the ratio of mesopores to its total pores volume of tectonic coals reduces to a large extent, the ratio of volume of micropores and the pores whose diameters are lower than micropores increases, and sub-micropores and ultra- micropores can be found. Moreover, the ratio of specific surface area of mesopores to its total pores reduces rapidly while the amount of sub-micropores increases more quickly. The ductile structure coal has a change in pore parameters similar to that of weak brittle deformation. There are differences in the deformation and evolution of nano-scale pore structure of different kinds of tectonic coals formed in different metamorphic-deformational environments. In short, temperature and confining pressure play some role in the change of nano-scale pore structure parameters, whereas stress has important influence on the evolution of characteristic parameters in nano-scale pore structure of tectonic coals.

作 者： JU Yiwen JIANG Bo HOU Quanlin WANG Guiliang   作者单位： JU Yiwen(College of Mineral Resource and Geosciences, China University of Mining and Technology, Xuzhou 221008, China;Laboratory of Computational Geodynamics, College of Geosciences, Graduate University of Chinese Academy of Sciences, Beijing 100049, China)

JIANG Bo,WANG Guiliang(College of Mineral Resource and Geosciences, China University of Mining and Technology, Xuzhou 221008, China)

HOU Quanlin(Laboratory of Computational Geodynamics, College of Geosciences, Graduate University of Chinese Academy of Sciences, Beijing 100049, China) 

刊 名： 科学通报（英文版）  SCI 英文刊名： CHINESE SCIENCE BULLETIN  年，卷(期)： 2005 50(16)  分类号： P618  关键词： coal structure   nano-scale deformation   macromolecular structure   pore structure   metamorphic-deformed environment  

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