Microstructure Characteristic and Adsorption Mechanism of Deformed Coal
|School||Henan Polytechnic University|
|Course||Mineral prospecting and exploration|
|Keywords||coalbed gas deformed pore structure adsorption-desorption|
This paper, selected fat-coal of the twelfth mine in Pingdingshan and blind-coal ofZhongma mine in Jiaozuo, did the high temperature and high pressure experiment,compared the structures of experiment deformed coal and natural deformed coal,carried out the mercury injection experiments and the isothermal adsorption-desorptionexperiments, analyzed the relations of coal structure and pore structure and the effectsof gas adsorption, studied CH4adsorption-desorption character. The research resultswill provide a certain guiding significance for coal-bed gas exploration-developmentand gas prevention.Through high temperature and high pressure experiment to coal, on condition thatwas the same strain rate and different strain capacity, studied coal deformedcharacteristics. The results show, strain capacity of coal sample increase with theincrease of differential stress; on condition that the temperature and pressure is same,strength of blind coal is greater than fat-coal; Strain rate and strain capacity have animportant impact on the deformation properties of the coal and the structure features ofthe coal， to form differential coal structures with different strain capacity.It was used the mercury injection experiments to research the pore structure ofcoal samples, and expressed the porosity of the characteristics of coal samples fromsize distribution, volume distribution, specific surface area distribution and medianaperture, also used the fractal theory to research the characteristics of coal surface. Fatcoal has obvious fractal features when the aperture is greater than62.5nm, anddifferent structure of the blind coal with different fractal aperture lower limit in orderfor120.8nm,95.3nm,62.6nm and40.3nm. The fat-coal fractal dimension is greaterthan the blind coal fractal dimension. The fractal dimension of fat-coal and blind coalgets big with the damage of coal deepening.Through the characteristics study of coal to CH4isothermal adsorption-desorption,the results show that the rank of coal plays an important controlling role on adsorptionability, the Langmuir volume of balance water coal samples regularity increases withthe increase of coal rank; The adsorption properties were similar between experimentaldeformed coal of blind coal and fragmentation coal and crushed coal, to provide opportunities for study deformed coal adsorption properties in the deep unmined seam. For different structure offat coal and anthracite coal, water has more affect than temperature on adsorptionprocess of coal; due to the different of experimental temperature and structure of coal,coal has different performance that CH4adsorption-desorption is reversible or not,desorption curve lags behind the adsorption curve.