| It is short of petroleum and gas but rich in coal in our country, and coal is the mainenergy which is an important strategic position in national economy and socialdevelopment. The prediction results of Coal and CBM resource shows that there areabundant coal and CBM resource in the deep coalbed of our country. Virtually, theadsorption of coal and coal reservoir is solid, gas, liquid three-phase media couplingresult in a certain temperature and pressure. Gas (CBM) and coal are generated at thesame time and methane as the main component and mainly adsorbed into the coalbed,the adsorbability of coal bed is the one of key factor to effect gas content. Thecontrolling mechanism of changes of deep coalbed three-phase medium to coal adsorbgas is unclear.Facing the problem of gas disaster prevention and control of deep coalbed mining,in drawing on previous research results and based on coal petrology, gas (CBM)geology, mechanics, physical chemistry and interface chemistry, statisticalthermodynamics, physical modeling and numerical simulation theory and otherdiscipline theory, analyse the variation of deep coalbed temperature, pressure andthree-phase media (solid, liquid and gas), selecting four coal samples that lignite fromBeizao mine, Longkou mining area, Shandong province, gas coal from Caiyuan mine,Weishan, Jining Shandong province, coking coal from Xiqv mine, Gujiao mining areaShanxi province and anthracite from Guhanshan mine Jiaozuo mining area, Henanprovince as the study samples, comprehensive use the methods of routine test, porestructure test, chemical composition analysis and others to do high temperature highpressure adsorption experiment of coal samples at different moisture content anddifferent concentration proportion of the gas mixture, coupling analyse the effect oftemperature, pressure, moisture, coal rank, microstructure and petrological composition,chemical composition and other characteristics for gas adsorption, exploring thedynamic control mechanism of adsorbtion on coal at high temperature and high pressurethree-phase medium. The coal fracture dimension was introduced to characterize itsinhomogeneity of complex structure and to establish the Fractal-Langmuir mathematicalmodel base on the physical adsorption theory of inhomogeneous solid. The study shows that the geological features of deep coalbed are high temperature,high pressure and low water content. The coalbed temperature increases with the burialdepth increasing, but it causes low adsorption and low moisture content with thetemperature elevated. While the the adsorption increased because of the elevatedmoisture content.The experiment results show that the VF-Lof wood coal decreases withincreasing temperature, but it is in contrast with the situation about coking coal. In thesame pressure conditions, there are differences in the effects of the different coal rank,temperature and moisture on the adsorption of coal. So, the characteristical results ofthis adsorption experiments are due to the combined effects of temperature and pressureand water content. The coal samples of equilibrium water corresponding to thetemperature shoud be selected and the highest experimental pressure is usually set to1.2times the actual coalbed to carry out adsorption experiments on deep coalbed. There arefeatures of the theoretical significance of widespread and high accuracy on theFractal-Langmuir adsorption model. |
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