地面钻井抽采老采空区瓦斯的理论与应用研究

发布时间：2018-02-03 18:24

本文关键词： 老采空区瓦斯地面钻井煤与瓦斯共采绿色开采　出处：《中国矿业大学》2013年博士论文　论文类型：学位论文

【摘要】：老采空区瓦斯抽采技术是将老采空区内遗煤、煤柱及邻近煤岩层不断解吸释放的瓦斯抽采至地面的煤矿瓦斯抽采技术，是煤与瓦斯共采技术体系的重要组成部分。老采空区瓦斯富集规律、老采空区裂隙场横向分布特征、地面钻井井位选择及井网布置是老采空区瓦斯资源开发亟待解决的关键问题，而我国老采空区瓦斯抽采技术研究起步较晚，相关基础理论研究仍处于空白阶段。针对上述问题，本文结合“十二五”山西省科技重大专项(20111101004)开展了地面钻井抽采老采空区瓦斯的理论研究。理论分析了老采空区瓦斯的赋存状态，揭示了老采空区瓦斯的来源，根据采动上覆瓦斯卸压运移“三带”理论确定了老采空区瓦斯的赋存范围，在此基础上利用分源法建立了老采空区瓦斯储量预测模型。在明确采空区导气裂隙带发育高度的基础上，将导气裂隙带在横向上划分为：侧向裂隙区、“O”形圈裂区和重新压实区，就工作面采高、覆岩关键层结构及采深对各横向分区发育形态的影响进行了数值模拟研究。研究结果表明：工作面采高是影响各横向分区发育形态的主要因素，侧向裂隙区超出开采边界的最大距离、“O”形圈裂隙区宽度均随工作面采高的增大而增大，在此基础上给出了考虑工作面采高、覆岩关键层结构及采深的各横向分区发育特征的判别方法，研究结果对老采空区瓦斯地面抽采钻井的井位选择和井网布置具有重要指导意义。通过自行研制的“采空区瓦斯抽采模拟试验系统”开展了老采空区地面井位优化的物理模拟试验研究，结果表明：地面钻井的抽采混合量整体呈不断衰减趋势，当抽采负压相同时，位于“O”形圈裂隙区的钻井抽采混合量较大，瓦斯浓度有小幅上升，“O”形圈裂隙区是地面钻井布置的最佳区域。对采空区覆岩垂直位移进行了监测，拟合得到了采空区覆岩垂直位移空间分布函数，在此基础上推导了采空区渗透率的空间分布函数，建立了老采空区瓦斯渗流数学模型，并通过FLUENT软件对该数学模型进行了求解。研究结果表明：布置在“O”形圈裂隙区内的地面钻井控制范围较大，，湍流区面积较大，随着地面钻井不断深入采空区中部的压实区，地面钻井控制范围不断减小，湍流区面积也不断减小。将老采空区瓦斯抽采的基础理论应用于阳泉矿区的老采空区瓦斯抽采试验，利用老采空区横向连通及纵向连通判据，对阳泉三矿老采空区进行了区域划分。利用老采空区瓦斯储量预测模型，对各连通区域的老采空区瓦斯储量进行了预测，确定了首批地面钻井的施工区域。根据地面井位优化和地面钻井控制范围的研究结果，指导了阳泉三矿老采空区地面井位选择和井网布置。
[Abstract]:The gas extraction technology in the old goaf is a kind of gas extraction technology which continuously desorption and release gas from the old goaf coal pillar and adjacent coal strata to the ground. It is an important part of the technical system of coal and gas mining. The law of gas enrichment in old goaf and the transverse distribution characteristics of fracture field in old goaf. The selection of well location and the layout of well pattern are the key problems to be solved urgently in the development of gas resources in the old goaf, but the study of gas extraction technology in the old goaf of our country started relatively late. The relevant basic theory research is still in the blank stage. In this paper, the theoretical study on gas extraction from old goaf by surface drilling is carried out in combination with the "12th Five-Year Plan" important scientific and technological project of Shanxi Province (20111101004). This paper theoretically analyzes the state of gas occurrence in the old goaf, reveals the source of gas in the old goaf, and determines the scope of gas occurrence in the old goaf according to the theory of "three zones" of overlying gas pressure relief and migration. On this basis, the gas reserves prediction model in the old goaf is established by using the source separation method. On the basis of defining the development height of gas conduction fracture zone in goaf, the gas conduction fracture zone is divided into lateral fracture area, "O" ring crack area and re-compaction area, and the face mining height is obtained by dividing the gas conduction fracture zone into lateral fissure zone, "O" circle crack zone and re-compaction area. The influence of the structure and mining depth of the key strata of overburden on the development of each transverse zone is studied numerically. The results show that the mining height of the working face is the main factor affecting the development of each transverse zone. The width of "O" ring fissure area increases with the increase of mining height, and the mining height is considered on the basis of the maximum distance of lateral fissure area beyond the mining boundary. The method of distinguishing the structure of overburden key strata and the development characteristics of each lateral zoning of mining depth is of great significance for the selection of well location and well pattern arrangement for gas extraction drilling on the ground in old goaf. Through the self-developed "gas drainage simulation test system in goaf", the physical simulation test of the ground well location optimization in the old goaf is carried out. The results show that the mixture of extraction and production of surface drilling is decreasing continuously. When the negative pressure of extraction is the same, the mixture of extraction and production is larger and the gas concentration is slightly increased in the fissure area of "O" ring. The "O" ring fissure area is the best area for surface drilling arrangement. The vertical displacement of overburden in goaf is monitored and the spatial distribution function of vertical displacement of overburden in goaf is obtained by fitting. On this basis, the spatial distribution function of goaf permeability is derived, and the mathematical model of gas seepage in old goaf is established. The mathematical model is solved by FLUENT software. The results show that the surface drilling in the "O" ring fissure area has a large control range and large turbulent area. As the ground drilling continues to penetrate into the compaction area in the middle of the goaf, the control range of the ground drilling and the area of the turbulent zone are also decreasing. The basic theory of gas drainage in the old goaf is applied to the test of gas drainage in the old goaf in Yangquan mining area, and the criteria of transverse and longitudinal connectivity of the old goaf are used. The old goaf of Yangquan No. 3 Coal Mine is divided into regions and the gas reserves of the old goaf are predicted by using the gas reserves prediction model of the old goaf. According to the research results of ground well location optimization and ground drilling control range, the selection of surface well location and well pattern arrangement in old goaf of Yangquan No.3 Mine are guided.
【学位授予单位】：中国矿业大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TD712.6

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