松软煤层钻进钻杆传力特性与煤体动力波动辨识

Soft coal seams containing high gas exist in over 50% of coal mines across China. Gas drainage using underground boreholes is the main gas control and utilization method in such places. Unfortunately, this method has technical problems which include shallow drilling depth, low drilling efficiency and frequently engineering accidents. Its result can have the serious influence to the gas drainage efficiency, and restricting mine to achieve the safety and high-efficient exploitation. The main reason for the difficulty of soft coal drilling is that the borehole collapse and gas blowout due to the fluctuation of gas pressure and crustal stress of coal seam. Drill bit mechanics analysis experimental facilities will be developed, the tests of the conventional drilling, drill bit mechanical analysis of coal mass dynamic fluctuation will be conducted, and the regulative mechanism of drill bit mechanic characteristics driven by the fluctuation of gas pressure and crustal stress of coal seam will be analyzed with the help of tests results. Drill pipe mechanics analysis test system will be developed, the tests of the mechanical analysis on thrust and torque of drill pipe will be conducted at different confining pressure, rotation speed and drilling speed, and the mechanical characteristics of drill pipe transmission rod body and drill bit will be explored. The model of identification on dynamic fluctuation of coal mass drilling in gassy soft coal seam will be established matching with hydraulic control system of drilling rig, probing and identifying methods on different types of coal mass dynamic phenomena will be explored under engineering conditions. This research results can provide theoretical basis and tests datum for drilling engineering of gas drainage in mining areas that contain soft coal seams and the development of intelligent drilling technology.

我国50%以上的煤矿赋存有松软高瓦斯煤层，松软煤层瓦斯治理与利用主要依靠井下钻孔抽采，但松软煤层钻进存在着“钻孔短、效率低、事故多”的难题，严重影响瓦斯抽采效率，制约煤矿安全高效开采。钻进过程中煤体瓦斯压力、地应力波动诱发钻孔塌孔、喷孔等动力现象是造成软煤钻进困难的主要原因。本项目研制钻头力学分析实验装置，进行常规钻进、煤体动力波动区钻头力学分析实验，分析瓦斯压力、地应力波动对钻头力学特征的调控作用机制；搭建孔内钻杆力学分析实验系统，进行围压、旋转速度、钻进速度变化条件下钻杆推力、扭矩力学测试实验，探索钻杆传递杆体及钻头力学特征的表征方法；建立与钻机液压控制系统相匹配的煤体动力波动智能辨识模型，探寻工程条件下不同类型煤体动力现象的预判及识别方法。研究成果为解决我国松软煤层矿区瓦斯抽采钻进工程面临的难题、推动复杂煤岩层智能化钻探技术发展提供理论基础和实验数据。

松软煤层瓦斯治理与利用主要依靠井下钻孔抽采。松软煤层钻进过程中煤体瓦斯压力、地应力波动诱发钻孔塌孔、喷孔等动力现象是造成钻具阻力大、钻孔困难的主要原因。研究钻具在孔内的力学特征及对钻孔动力现象的识别机制是自适应智能钻探技术发展需要解决关键问题之一。本项目开展了动载荷作用下含瓦斯软煤岩钻进钻头受力特征、煤体动力波动对钻头力学特征的调控机制、钻孔受限空间内钻杆力学特征、钻进过程中煤体动力波动智能辨识模型等方面的研究。主要研究成果为：建立了钻头推力损失和扭矩损失力学模型，并获得相应的求解方程，分析了钻进推进速度、煤体强度、气流压力等参数变化对钻头力学特征的影响规律；开展了竖直恒定荷载循环作用下钻孔相似模型试验，明晰了松软煤层钻进钻孔失稳演化特征，结合动载荷作用下钻进钻头受力特征，分析了瓦斯压力波动、钻遇构造等情况下对钻头受力特征的影响；建立了钻孔受限空间内钻杆悬空、触底状态力学模型，获得了钻杆推力损失、扭转损失的求解方程，结合钻进模拟试验，定量分析了钻孔受限空间内钻杆的力学特征；建立了钻孔收缩、堵塞塌孔段钻杆力学模型，获得了钻具扭矩损失、推力损失的求解方程，结合AMESim钻进系统仿真模型，分析了煤体瓦斯压力、地应力波动诱发钻孔收缩、塌孔等动力现象的预判和识别方法。研究成果为提高煤矿井下复杂煤岩层钻孔施工效果、实现煤矿井下智能化钻探提供了理论基础。