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煤矿区煤层气“四区联动”井上下联合抽采模式与技术体系

Mechanism and technical system of ground and underground combined drainage of CBM in “four region linkage” in coal mining area

  • 摘要: 为了更好地实现高瓦斯矿区煤炭与煤层气2种资源的安全高效协调开发,在“十一五”“十二五”研发的煤层气“三区联动”立体抽采模式基础上,依托“十三五”国家科技重大专项持续攻关,并紧密结合山西重点煤矿区生产实际,创新研发了全矿区、全层位、全时段的煤矿区煤层气“四区(规划区、准备区、生产区、采空区)联动”井上下联合抽采模式(新晋城模式)和系列技术体系,在山西重点煤矿区得到广泛应用并取得了良好效果。煤矿规划区煤层气地面抽采技术早期主要采用垂直井、定向井、水平井等技术,现已发展至以分段压裂水平井为主导的井工厂化集约开发模式与技术。经十五年的地面超前预抽,晋能控股寺河矿东五盘区3号煤层平均降幅超过55%,该盘区的5310、5311工作面已顺利完成安全高效采煤,实现了高瓦斯煤层的低瓦斯开采。准备区煤层气井上下联合抽采技术充分利用了压裂影响区渗透率大幅提升和井下开放空间抽采生产压差增大的优势,构建了立体抽采网络,提高了煤层气抽采效率,有效缓解了矿井抽掘采接替紧张,促进了高产高效。基于生产区采动活动剧烈和井下工程全开放特点,运用定向钻机精准完成区域递进式顺层钻孔、穿层钻孔、高位定向长钻孔等,精准均衡抽采生产区煤层气,有效解决了常规钻孔轨迹不可控、易形成抽采盲区、抽采效果差等难题,实现了生产区井下抽采精准达标,确保万无一失。针对煤炭采空区煤层气资源赋存规律不清、资源量评估困难、安全钻采技术缺乏等难题,创建了采空区煤层气资源量计算方法,研发了煤矿采空区地面钻采系列技术,已在晋城、西山、阳泉等山西重点煤矿区完成了129口井的示范推广,累计抽采利用煤层气1.28亿m3,相当于减排二氧化碳192万t。“四区联动”井上下联合抽采模式和系列技术体系在山西重点煤矿区的成功,有效实现了煤层气 “减少温室气体排放、保障煤矿安全生产、补充绿色气体能源”三重功效,为我国煤层气产量由2006年的25.8亿m3提升到2020年的191.7亿m3提供了有力的支撑,同时也为山西重点煤矿区煤炭采深逐年加深、矿井生产条件日趋复杂、生产矿井数量持续减少、煤炭总产量稳步增长提供了有效的保障。

     

    Abstract: In order to better realize the safe and efficient coordinated development of coal and CBM resources in high gassy mining areas, the four regions (planning region, preparation region, production region and coal mined-out region) linkage ground-underground combined drainage mode (new Jincheng mode) and a series of technical systems of CBM in the whole mining area, all stratum layer and all time were innovatively developed. Relying on the “Thirteen Five - Year Plan” national major science and technology projects to continue to tackle key problems, closely combining with the actual production of key coal mining areas in Shanxi Province. This new mode upgraded from the “three regions linkage” three-dimensional extraction mode of CBM developed during the “Eleventh Five-Year” and the “Twelfth Five-Year” Plan and it had been widely used in key coal mining areas of Shanxi Province and achieved good results. The ground pre-drainage technology of CBM in the planning area mainly used vertical wells, directional wells, horizontal wells and other technologies in the early stage. But now it had developed into a well factory intensive development mode and technology dominated by multi-fractured horizontal well. After 15 years of ground pre-drainage, the average reduction of No.3 coal seam in East Fifth Panel of Sihe Mine of Jinneng Holding Group had reached 55%. The No.5310 and No.5311 working faces in this panel had successfully completed safe and efficient coal mining, realizing low gas mining in high gas content coal seam. The ground-underground combined drainage technology of CBM in the preparation region made full use of the advantages of the greatly increased permeability in the fracturing affected area and the increased production pressure difference of underground open space drainage. Which formed a three-dimensional drainage network, improved the drainage efficiency, effectively alleviated the tension in the replacement of mining, and promoted high production and efficiency.Based on the characteristics of intense mining activities in the production area and full opening of underground projects, directional drilling rigs were used to accurately complete regional progressive seam drilling, through hole drilling, and high directional long borehole, and accurately and evenly extract the CBM in the production region. This effectively solved the problems of uncontrollable conventional drilling trajectory, easy to form blind areas for drainage, and poor drainage effect, and realized the accurate standard of underground drainage in the production region, ensuring no risk.In view of the problems such as unclear occurrence law of CBM resources in the coal mined-out region, difficulty in resource assessment, and lack of safe drilling and mining technology, the calculation method of CBM resources in the coal mined-out region was created. And a series of technologies for ground drilling and mining in coal mined-out region were developed. 129 wells had been demonstrated and promoted in Shanxi key coal mine areas such as Jincheng, Xishan, Yangquan, etc., 128 million cubic meters of CBM had been pumped and utilized, and 1.92 million tons of carbon dioxide had been reduced.The success of the ‘four region linkage’ ground-underground combined drainage mode and a series of technical systems in key coal mining areas of Shanxi had effectively achieved the triple effect of CBM “reducing greenhouse gas emissions, ensuring coal mine safety production, and supplementing green gas energy”. Which provided strong support for China’s CBM production to increase from 2.58 billion cubic meters in 2006 to 19.17 billion cubic meters in 2020. At the same time, it also provided an effective guarantee for the deepening of coal mining depth year by year in key coal mining areas of Shanxi Province, the increasingly complex mine production conditions, the continuous reduction of the number of production mines, and the steady growth of the total coal output.

     

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