CFD模型下采空区瓦斯抽采与防火研究

发布时间：2018-04-20 01:29

本文选题：地面钻井 + 瓦斯抽采　；参考：《中国矿业大学》2017年硕士论文

【摘要】：作为高瓦斯复杂煤层群开采的典型,淮南矿区在煤与瓦斯共采领域取得了很大成功。本文以地面井产气成功率较高的丁集矿为研究矿区,对保护层开采下采空区卸压瓦斯分布规律、钻井抽采下采空区瓦斯运移规律、抽采下采空区三带分布变化和地面钻井优化布置进行了系统研究,以瓦斯涌出量大小为依据,提出了针对含瓦斯易自燃煤层采空区注氮、合理抽采等综合防治技术。结合采空区高位环形裂隙体理论,确定了地面井布置的最佳位置,考察分析了丁集矿保护层工作面开采下钻井产气量随采动的变化关系,对卸压瓦斯流态特征、地面钻井防破坏措施、施工要点与产气变化规律等问题进行了总结。以计算流体力学模拟软件FLUENT为研究工具,编制自定义函数设置采空区渗透率分布、瓦斯涌出量大小等参数,模拟得出了地面井抽采下采空区瓦斯运移分布规律及抽采对采空区三带分布的影响:(1)钻井抽采会在采空区形成低压区,增大氧气从周围裂隙向采空区的侵入范围,采空区气体流场分布与钻井布置位置相关。浅部地面井抽采能更有效地降低回风巷瓦斯浓度,高浓度瓦斯可在深部形成惰化区。深部地面井可抽采上被保护层卸压释放的高浓度瓦斯,但更容易将氧气向采空区深部转移,尤其大流量抽采时使深部氧气含量急剧增大。(2)井上下立体抽采易使得采空区内部漏风通道间相互贯通,采空区注氮可很好地惰化采场进风侧与深部区域,在相同注氮流量下,采空区深部注氮比浅部注氮可更有效地惰化整个采场,但回风侧由于漏风强烈使得氮气流失,存在氧化高温区。(3)联合钻井抽采可在采空区内形成较为均匀分布的低压区,对大走向采空区能合理地分配抽采能力,在保证抽采浓度的同时,不会导致采空区富氧带范围急剧扩大,能最大化抽取采空区卸压瓦斯。(4)矿井瓦斯涌出量小于40m3/min时,采用井下瓦斯抽采即可很好的治理瓦斯超限问题,瓦斯涌出量大于40m3/min是,需综合采取矿井上下立体抽采措施,才可有效控制瓦斯超限问题。淮南丁集矿区保护层卸压瓦斯井上下立体抽采工程实践表明,瓦斯抽采流量随工作面推进引起的采动裂隙演化而发生变化,地面钻井的抗破坏能力对于瓦斯高效、长期抽采有很大影响。在钻井成功的情况下,高效抽采可以持续6个月以上的时间,工作面收作以后,仍可抽采卸压与采空区积聚瓦斯,有效抽采周期最长达3年以上。丁集矿考察期间地面钻井抽采的月平均抽采纯流量6.32~14.27m3/min,累积总抽采纯量16635631m3,占总抽采量的27.52%。工作面高抽巷和顶板钻孔的月平均抽采纯流量2.87~20.63m3/min,累积总抽采纯量30326880 m3,占总抽采量的50.16%。地面钻井、井下高抽巷和走向钻孔抽采瓦斯浓度较高、时间较长,不影响井下煤炭生产,可有效治理高瓦斯煤层的瓦斯灾害问题。论文的研究高瓦斯矿井瓦斯治理与瓦斯抽采过程下自燃防治有一定的参考和借鉴意义。
[Abstract]:As the typical mining of high gas and complex coal seam group, the Huainan mining area has made great success in the field of coal and gas CO production. This paper takes the Buji mine with high success rate of the ground gas production as the research area, the distribution law of pressure relief gas distribution in the goaf under the protection layer, the law of gas migration in the goaf under drilling, and the three band in the mined out area under extraction. On the basis of the size of gas emission, the comprehensive prevention and control technology for nitrogen injection and reasonable extraction in goaf containing gas and easy spontaneous combustion coal seam is put forward on the basis of the size of gas emission. The gas flow rate under the working face is dependent on the change of production, the characteristics of pressure relief gas flow pattern, ground drilling anti failure measures, construction key points and gas production change law are summarized. The calculation of fluid mechanics simulation software FLUENT is used as the research tool to set up the permeability distribution in the goaf area and the gas emission is large. The distribution law of gas migration in the mined out area under ground well extraction and the influence of extraction on the three belt distribution in the goaf are simulated. (1) the drilling extraction will form a low pressure area in the goaf, increase the invasion range of oxygen from the surrounding fissure to the goaf, and the distribution of gas flow field in the goaf is related to the location of the drilling layout. The gas concentration in the return air lane can be reduced more effectively. The high concentration gas can form the inert area in the deep part. The deep ground well can extract the high concentration gas released by the protected layer, but it is easier to transfer the oxygen to the depth of the goaf, especially in the large flow extraction, which makes the deep oxygen content increase sharply. (2) the well and lower solid extraction is easy to make goaf. The inner air leakage channel interconnects each other, and the nitrogen injection in the goaf can inert the inlet and deep regions well. Under the same nitrogen injection flow, the deep injection of nitrogen in the goaf is more effective to inert the whole stope more effectively than the shallow nitrogen injection, but the air leakage is strongly caused by the leakage of air, and there is a high oxidation temperature zone. (3) joint drilling extraction can be used in mining. The relatively uniform distribution of the low pressure area in the empty area can reasonably distribute the pumping capacity in the large goaf. While the extraction concentration is guaranteed, the range of the oxygen rich zone in the goaf will not be greatly expanded. (4) when the gas emission of the mine is less than 40m3/min, it is good to adopt the underground gas extraction. In order to control the problem of gas exceeding the limit, the gas emission is more than 40m3/min, so it is necessary to take the comprehensive extraction measures on the upper and lower sides of the mine to effectively control the problem of gas overlimit. The practice of the upper and lower solid extraction engineering of the pressure relief gas well in the protective layer of the Huainan Ding Ji mining area shows that the gas extraction flow changes with the evolution of the mining fracture caused by the advance of the working face. The anti destructive ability of ground drilling has a great influence on gas efficiency and long-term extraction. In the case of successful drilling, high efficiency extraction can last more than 6 months. After the work face is collected, the gas discharge pressure and the accumulation of gas in the goaf can still be accumulated for more than 3 years. The average monthly pumping rate is 6.32~14.27m3/min, and the total extraction purity is 16635631m3. The monthly average extraction pure flow rate is 2.87~20.63m3/min for the high pumping and roof drilling in the 27.52%. working face of the total extraction. The cumulative total extraction purity is 30326880 m3, which accounts for the 50.16%. ground drilling of the total extraction, and the gas concentration in the underground high pumping and drilling holes is more than that of the drilling. It has a long time and does not affect the production of coal mine. It can effectively control the gas disaster of high gas coal seam. This paper has a certain reference and reference significance for the study of gas control in high gas mine and the prevention and control of spontaneous combustion under the process of gas extraction.

【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD712.6;TD75

【参考文献】