| Tectonic coal is formed under the effect of tectonic stress, and the coal endure the embrittlement, damage, ductile deformation or combination of all. Tectonic stress in different periods, different types produced different types of tectonic coal. Mainly include three series: ductile deformation an, brittle deformation and brittle ductile transition three series.Relative to the undisturbed coal, tectonic coal usually have a large amount of gas adsorption, gas adsorption-desorption rate and low rate of penetration,which make the coal seam that have tectonic coal generally easy to gas concentration in great quantities and cause changes in the form of coal mechanics.All the factors contribute to the gas outburst accident.Due to the characteristics of tectonic coal,it generally contains a large amount of coalbed methane resources. With coal mining, a lot of coal gas, coal-bed methane, a large amount of emissions put into the atmosphere, not only cause the waste of resources, but also cause the nvironmental ollution.Therefore, how to make good utilization of CBM resource with the safety in the In process of mining has become a new topic.To solve above problems, We provide basic theory for mining of coal bed methane and comprehensive control of gas from the perspective of muultiple,like:geological investigation, scanning electron microscope observation and dsorption and desorption experiment of tectonic coal.This thesis mainly get the following progress:(1)With the perspective of structural geology, from field investigations to laboratory analysisWe analyze the factors of coalbed gas generation, migration, occurrence and enrichment.At the same time find the key factor to the whole process of the coalbed methane formation.Including①structural dynamics, structural evolution and control role;②control ofdeposition formatio and coal reservoir space distribution;③coal rheology, layer slip and its control mechanism.(2)In order to study the adsorption capacity of lump coal samples including undisturbed coal, cataclastic coal,flaky coal and mylonitic coal all taken from Hancheng mining area under the condition of same temperature and same initial pressure,a coal sample test device had been designed for testing the capacity of gas adsorption and desorption. The results shows that the tectonical coal samples have the higher amount of gas adsorption than undisturbed coal at the condition of adsorption equilibrium, cataclastic coal,flaky coal and mylonitic coal are estimated to be2.11,2.26and2.52times of that of undisturbed coal. Adsorption rate of undisturbed coal and tectonic coal are all assumed as a monotone decreasing curve. In the initial stage,especilly0～2min period, there is a big gap between tectonic coal and the undisturbed coal in adsorption rate and the gap is narrowing over time. Tectonic coal have the higher efficiency and reach the adsorption equilibrium in less time. In addition, due to its good compactness and the state of initial fissure the undisturbed coal have significantly stronger gas "seal" ability than tectonic coal.(3)In order to reveal the nature of coal bed gas generation, migration and enrichment regularity and to study micro structure of coal body from coal reservoir pore-fracture structure, pore shape, connectivity, porosity by the means of scanning electron microscope observation.From microscopic perspective reveals the truth of the block coal and native structure block tectonic coal in different types of gas adsorption performance difference.Good porosity and fracture development determines the tectonic coal samles have the higher capacity of gas adsorption than the undisturbed coal.Different proportions in Large, medium and small and micro pore development contribute to the different adsorption performance of of tectonic coal. |
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