【作者】 李伟；

【导师】 程远平；

【作者基本信息】 中国矿业大学 ， 安全技术及工程， 2011， 博士

【摘要】 窑街矿区是目前我国唯一开采的具有煤与CO2突出危险性的矿区,突出灾害严重,井田主采煤层中赋存瓦斯以CO2为主,且国内外对煤田中CO2的成因赋存演化以及防治煤与CO2突出技术研究的相对较少,现有的对窑街矿区CO2的认识与CO2治理技术措施尚不能有效保证矿区的安全高效生产。本文以窑街海石湾井田为研究背景,以海石湾井田煤二层中CO2为主要研究对象,运用地球化学、岩石学、构造地质学、表面物理化学、岩石力学、采矿工程、渗流力学、数值模拟等多学科理论,采用理论分析、实验室实验与现场工程实践的研究方法,系统地开展了井田CO2成因、CO2成藏规律、CO2的赋存状态、海石湾煤对CO2的吸附解吸特性、孔隙压力对煤层卸压作用机制以及工程实践等多方面的研究,并取得了一定的创新成果,本文的主要研究结论如下：1)根据对海石湾井田煤二层中CO2的碳同位素与氦同位素测定结果,实测海石湾井田主要测点的CO2含量均大于60%,实测δ13CcO2变化范围主要为+1.00～-5%‰,3He/4He测定值均为10-8数量级,R/Ra为0.0042～0.185,分析认为海石湾煤田中CO2为无机地壳来源。并根据F19断裂构造岩性质、多期运动性以及实验分析,提出了海石湾井田CO2为F19韧-脆性剪切带的动力变质成因；且F19断裂在井田CO2成藏过程中起到了成气断裂、输气断裂和封气断裂的多重作用。2)建立了修正的D-A模型,该模型对现有的高压吸附实验数据具有较高的拟合精度,并对海石湾煤对超临界CO2吸附等温线进行了分析,引入了聚合物的自由体积理论对异常吸附等温线进行了理论分析,并得到了解吸曲线的初步验证。3)海石湾井田煤二层埋深600～1000m时,地温为31.72℃-43.88℃、实测最大瓦斯压力为7.3MPa、井田东部CO2浓度超过90%,计算海石湾井田东部区域的混合瓦斯含量达到50-60m3/t,现场测定、实验测定以及理论计算结果表明,海石湾井田煤二层中赋存超临界CO2。4)数值模拟结果表明,随着保护层工作面推进,下伏煤岩体的采动卸压范围、及煤二层的膨胀变形量均随着孔隙压力的升高而增大,最大绝对变形量为328mm,最大相对变形量可达5‰,随着保护层推进与孔隙压力的增大,被保护层发生塑性破坏并随之增大,并进行了理论分析,结果表明孔隙压力在增强被保护层卸压中起着重要作用。5)远距离上保护层开采及卸压瓦斯抽采实践验证了高孔隙压力在煤层卸压中的作用,抽采单孔流量达到2m3/min以上,煤层透气性增大878倍,煤层瓦斯含量由53m3/t降至12m3/t,消除了煤二层的突出危险性,同时工程实践也验证了本文提出的相关结论。本论文有图110幅,表20个,参考文献158篇。更多还原

【Abstract】 The Yaojie Coalfield is the only mining area with coal and CO2 outbursts in China. The CO2 is featured as the dominant gas component in coal seam. This paper takes the Haishiwan Coalfield as the background and the No.2 Haishiwan mine area as the main study object, systematically carrying out study of various aspects on the causes of CO2, CO2 enrichment regularity, CO2 occurrence in coal seam of the Yaojie Coalfield, adsorption and desorption of CO2 in coal, numerical simulation and engineering practice applied to eliminate the risk of coal and CO2 outburst regionally. The main conclusions are as follows:1) The CO2 originates from inorganic crust sources according to carbon isotope and helium isotope in the Haishiwan Coalfield. The dynamic-thermal metamorphism of the F19 ductile-brittle shear zone is believed to result in the CO2 release. The F19 fault plays multiple roles in the generation, transportation, and trapping of gas during the CO2 formation.2) Studies on the characteristics of coal absorbing CO2 or CO2/CH4 mixture are carried out under low pressure. The D-A model fits the adsorption isotherms of CO2 well under low pressure. The modified D-A model is applied to analyze the supercritical CO2 adsorption isotherms of Haishiwan coal and free volume theory is used to explain abnormal adsorption isotherms.3) Taking the temperature, pressure of supercritical CO2 occurrence and the change of critical point of CO2 and CH4 mixed gas occurrence into consideration, and combining the basic parameters consist of earth temperature, gas pressure, gas content, gas concentration and so on, we raised the hypothesis that occurrence of supercritical CO2 occurs in the No.2 of Haishiwan coal field.4) Numerical simulation is used to analyze the stress and strain, damage characteristics, and evolution of protected coal seam under different pore pressure in the stope. The mechanism obtained that pore pressure helpful to pressure relief in protected coal can be used for pressure relief CO2 drainage of protected coal seam.5) High pore pressure acts on pressure relief of coal seam, which has been verified in practice of remote protective coal seam mining and pressure-relief gas drainage. The singe gas drainage flow reaches more than 2m3/min. The coal seam permeability increases by 878 times. The gas content decreases from 53m3/t to 12m3/t. The risk of outburst has been eliminated with regard to the No.2 coal seam.更多还原