| Coal will occupy the dominant position in China's primary energy consumption structure for a long time.Gas disaster is still the main factor that restricts the safe,scientific and green development of coal mines in China.Before mining,it is necessary to comprehensively detect and analyze the occurrence state of gas geology,and quantitatively identify the source of gas emission disaster in the working face to guide and realize accurate governance.In practical production,the gas control project lacks quantified sub-source data guidance,including evaluation of pre-drainage effect of drilling through multiple coal seams at one time,emergency treatment of abnormal gas gush from unknown sources,and evaluation of relief and protection effect of protective layer in the face of protected layer.In order to solve these problems,it is necessary to systematically collect the gas desorption in each coal seam of the main mining system,scientifically test the stable carbon and hydrogen isotope data,and use rigorous mathematical analysis to carry out comprehensive analysis and research,so as to realize the quantification and separation of gas source and scientific control in the mining face.For accurate quantitative and dynamic reflect the characteristics of multi-source gas emission source structure,based on the southern qinshui basin Carboniferous-Permian Shanxi-taiyuan group main coal series strata typical geological section as the research object,the system master gas,on the basis of geological characteristics,the main coal series strata of organic carbon and its solutions of inspiratory test stable carbon isotope analysis,The correlation model of coal organic carbon and its desorption gas was established,the sedimentary environment of coal seam and the accumulation type of coalbed gas were analyzed,the distribution range and characteristic values of desorption stable carbon and hydrogen isotopes of different coal seam were obtained,and the distribution chart of desorption stable carbon and hydrogen isotopes of main coal series strata was drawn.Combination of mass conservation theorem with multiple source linear algorithm,based on stable carbon isotope and multi-source gas source points calculation model of linear algorithm,is applied in the study area based on the results of the study the main mining face goaf gas source analysis,reveals the goaf mixed gas sources dynamic evolution rule for the first time and the volume of a gas emission sources in each layer structure characteristics,The error source of the model was analyzed by parallel test and orthogonal test to verify the scientific nature and reliability of the research results.The results show that the main coal system strata of Sihe Mine present significant Marine and sea-land mutually complementary coal environment and sedimentary characteristics,and in the main coal system strata,the organic carbon isotopes of coal seam have obvious homologous contribution to the carbon isotopes of the elements in the desorption gas.It is found that the overall coal-forming environment and late diagenesis of the No.3 coal seam and its adjacent layers are basically the same,and the genesis mechanism of desorption gas is basically the same,which belongs to the single type thermal gas.There are differences in the values of desiccated components and stable carbon and hydrogen isotopes in each coal seam,which generally shows that the carbon and hydrogen isotopes gradually become heavier with the increase of burial depth.The dynamic change process of gas gushing in the goaf of the working face of the main coal seam along the strike adjacent layer presents a significant feature of stages,which can be divided into:the main stage of the coal seam flooding,the transition stage of the near adjacent layer flooding,and the stage of dynamic balance and stability.With the dynamic advance of the working face,the gas emission ratio of No.3 coal in the goaf gradually decreases and finally stabilizes at 20?25%.The coal seam in the near distance shows a characteristic of rising first,then falling and stabilizing,and finally stabilizes at 20-25%.The final gas desorption rate of No.9 coal is 20?25%,and that of No.15 coal is 30?35%.Compared with the traditional prediction of separate source,the stable carbon and hydrogen isotopes can quantitatively distinguish the volume ratio of gas emission between the coal seam and the adjacent layers during the mining process,and the result of phase prediction is more helpful to guide the design of gas control engineering than the result of source prediction.By 20 samples of system error analysis results show that the same mixture sample parallel test analysis of relative standard deviation was 0.16?5.22%,and the method of collecting gas affected by the error of carbon dioxide,carbon isotope,relative standard deviation of 30.1%,the need to adopt carbon dioxide carbon isotope values calculated method of four unkowns and five unkowns.The gas must be collected with a syringe.Two kinds of storage containers,headspace bottle and alum-plastic gas sample bag,were analyzed in the storage and transportation section.The orthogonal test was used to complete the error analysis with time intervals of 5 days and 20 days.The results showed that the absolute deviation of the alum-plastic gas sample bag could reach 1.98‰ and the relative standard deviation rate was 4.76%from the beginning of sampling to the testing interval of more than 20 days.Therefore,the 20-day sampling test interval should be stored and transported in headspace bottles to avoid the influence of errors.The research results provide a scientific basis for the precise prevention and control of gas disasters in the process of mining,and also have a guiding significance for the identification of risk sources of abnormal gas emission and the formulation of emergency technical measures.Figure[40]table[34]reference[167]... |
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