Research And Application Of The Microscopic Pore Structure Characteristics Of Low Permeability Coal Seam

There are nature connections between microscopic pore structure of coal seam and lotsof macroscopic phenomena or macroscopic properties in coal mining practice,and it is aneffective tool of understanding and interpretation of macroscopic phenomena or nature andhas an important value and meaning for the development and utilization of coal each regionby the research of microscopic pore structure.In this paper,the microscopic pore structure of low permeability coal seam in theShenhua Xiaohonggou coal mine located in Urumqi has been studied by the combinationmethods of field research,laboratory experiments and theoretical analysis,the main contentsand conclusions are as follows:(1) Through the cryogenic nitrogen adsorption method,the surface area,porevolume,pore size and pore distribution of the B1samples to B6samples from XinjiangXiaohonggou coal mine have been determined,the types of adsorption-desorption isothermsand the pore distribution of the various coal samples have been analyzed,two kinds of fractaldimension model including pore volume fractal model and pore area fractal model of the coalseam pore structure have been established,pointing out that either of two kinds of fractaldimension may reflect pore radius distribution of the coal seam samples,and concluding thatthe porosity radius distribution of the fractal dimension is an important parameter to describethe characteristics of the pore structure of coal,which reflects the inherent characteristics ofthe coal sample porosity and the complexity of pore structure of coal seams,and whichreflects the complexity of the porous media and the irregularities of pore shape.(2)Through the scanning electron microscopy experiments,the microscopic porestructure type and surface mineral particle size distribution and pore fracture mineral-filledsituation of coal seams samples have been observed and analyzed,these mineral particlescompositions have been specifically identified combined with the XRD experiments,pointingout that the presence of some special clay mineral which is a part of coal seam microscopic pore structure and will also have an important impact on the macroscopic properties.Inaddition,based on SEM images of data,two kinds of plane fractal dimension model includingpore area fractal model and pore distribution fractal model of the coal seam pore structurehave been established,pointing out that the magnitude relationship of two kinds of fractaldimension which both reflect the inhomogeneity of the pore distribution are essentially same.(3)Finally,through two cases of macroscopic applied research,the microscopic porestructure of coal has been in-depth continued to study,at the same time,the connectionsbetween the microscopic pores research and macroscopic properties or macroscopicphenomena of the coal seams have been revealed.First,the coal sample porosity andpermeability have been tested by laboratory experiments,the relationships between the fractaldimensions and porosity and permeability of all coal samples been analyzed,pointing out theconnections between the pore structure and the physical parameters of coal seams;and throughthe image processing of SEM image of the coal samples,the fractal coefficients of coal seammicroscopic pore structure have been extracted by the fractal tool,which have been used toaccurately descripte multi-scale property of the coal microscopic pore structure,furthermore,the multi-scale property has been successfully used for fluid transport mechanismexplanation.