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厚硬顶板冲击地压井下长钻孔压裂防治关键技术装备与工程实践

Key technical equipment and engineering practice of long borehole fracturing prevention and control in thick and hard roof rock burst underground

  • 摘要: 针对厚硬顶板诱发冲击地压的防控难题,突破传统局部卸压治理模式,开展井下长钻孔压裂关键技术与装备研究,建立超前时空协同的顶板弱化改造体系。基于“地质−应力−能量”协同作用理论,采用理论建模−装备研发−工程验证相结合的研究方法,通过构建三维判识模型、研发定向成孔装备、创新压裂工艺参数、开发监测评价系统等技术路径,系统开展厚硬顶板水力压裂防治技术研究。研究表明:① 建立的“地质结构−应力场特征−能量积聚度”三维判识模型,实现压裂目标层的多维度定量识别;② 研制的可变幅大倾角超高位成孔平台,倾角调节达50°,成孔效率提升20%以上,孔深可达1000 m以上,剖面高度可达100 m以上;③ 研发的低速大流量压裂泵组(排量2.8 m3/min,压力80 MPa)与多参量监测系统,实现压裂过程动态调控,同时搭建了在线监测装备体系,实现压裂全周期的系统监测及治理效果的科学全面评价;④ 在纳林河二矿典型顶板强冲矿井开展了工程试验,治理后,煤体应力较邻近面降幅均超60%;大能量微震事件频次及能量较本工作面非治理区域及邻近工作面降幅均在70%左右,周期来压步距缩短25%以上。从压裂裂隙网络弹性应变能耗散、缩短悬臂降低破断动能、分层垮落阻断动能传递路和高压水岩石弱化等多尺度协同作用机制,探讨了厚硬顶板定向长钻孔分段压裂“能量耗散−结构调控−路径阻断−强度弱化”卸压防灾机理。指出了构建数字孪生压裂参数智能优化平台和研发智能压裂成套装备发展方向,并提出单一防灾模式向“精准识别−智能调控−多灾联防”转型新思路。

     

    Abstract: Aiming at the problem of prevention and control of rock burst induced by thick and hard roof, breaking through the traditional local pressure relief treatment mode, the key technology and equipment of underground long borehole fracturing are studied, and the roof weakening transformation system with advanced space-time coordination is established. Based on the theory of “geology-stress-energy” synergy, the research method of combining theoretical modeling, equipment development and engineering verification is adopted. By constructing three-dimensional identification model, developing directional drilling equipment, innovating fracturing process parameters, developing monitoring and evaluation system and other technical paths, the research on hydraulic fracturing prevention and control technology for thick and hard roof is systematically carried out. The research shows that: ① The three-dimensional identification model of “geological structure-stress field characteristics-energy accumulation degree” is established to realize the multi-dimensional quantitative identification of the fracturing target layer. ② The developed ultra-high-position hole-forming platform with variable amplitude and large dip angle can adjust the dip angle to 50°, increase the hole-forming efficiency by more than 20%, the hole depth can reach 1000 m, and the profile height can reach more than 100 m. ③ The low-speed and large-flow fracturing pump group (displacement 2.8 m3/min, pressure 80 MPa) and multi-parameter monitoring system are developed to realize the dynamic control of fracturing process. At the same time, an online monitoring equipment system is built to realize the scientific and comprehensive evaluation of the whole cycle of fracturing system monitoring and treatment effect. ④ The engineering test was carried out in the typical roof strong-impact mine of Nalinhe No.2 Mine. After the treatment, the stress of the coal body decreased by more than 60% compared with the adjacent working face. The frequency and energy of large energy microseismic events are about 70% lower than those in the ungoverned areas and adjacent working face, and the periodic weighting step is shortened by more than 25%. From the multi-scale synergistic mechanism of elastic strain energy dissipation of fracturing fracture network, shortening cantilever to reduce fracture kinetic energy, layered collapse to block kinetic energy transfer path and high-pressure water rock weakening, the mechanism of “energy dissipation-structure regulation-path blocking-strength weakening” pressure relief and disaster prevention of directional long borehole multi-stage fracturing with thick and hard roof is discussed. It is pointed out that the development direction of constructing an intelligent optimization platform for digital twin fracturing parameters and developing intelligent fracturing complete sets of equipment, and puts forward a new idea of transforming a single disaster prevention mode to “precise identification-intelligent control-multi-disaster joint prevention”.

     

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