【作者】 刘震；

【导师】 李增华；

【作者基本信息】 中国矿业大学 ， 安全技术及工程， 2014， 博士

【摘要】 针对单一低透气性突出煤层区域防突问题，人们发展了多种水力化钻孔卸压增透抽采技术，如水力冲孔、煤层注水、水力压裂等，并取得了良好的应用效果，但是对于技术措施中作用于含瓦斯煤体的水分对煤层瓦斯渗流特性的影响机制缺乏深入的研究。本文围绕多种水力化措施中水分影响作用的共性，通过实验室试验、数值模拟及现场试验与应用，系统研究了水力化钻孔径向瓦斯渗流特性，并取得以下研究成果：（1）自主研发了水力化钻孔径向瓦斯渗流实验系统，可实现径向稳态/非稳态渗流实验、煤层注水驱气实验、液态水润湿及高压注水煤样等温吸附实验，同时可满足不同覆压、瓦斯渗流压力、气体种类、钻孔孔径、含水率条件下径向稳态渗流实验功能，以及不同注水流量下注水口压力及边界压力的实时监测。（2）基于径向稳态渗流实验，研究了瓦斯压力、吸附作用、覆压及钻孔卸压对煤体渗透率的影响规律。分析了煤层注水驱气动力学过程，实验测试了煤层注水驱气过程中煤样内、外边界压力演化规律，提出了注水驱气过程的四个阶段；实验研究了覆压、原始瓦斯压力、注水流量等因素对煤层注水驱气渗流特性的影响规律，并得出了注水钻孔周围煤体含水率分布规律。（3）提出了水力化钻孔径向瓦斯渗流物理模型，实验研究了物理模型中水分影响区域内煤体等温吸附特性及孔隙特征；测试了水/CH4竞争吸附对煤体渗透率的影响规律，以此建立了水分影响下煤层瓦斯渗透率的实验室测定方法，最终构建了CH4在湿煤中的渗透率预测模型，并通过实验予以验证。（4）数值模拟了不同预抽时间、水力冲煤孔径、原始瓦斯压力、渗透率模型下钻孔径向流场分布规律，验证了水力化钻孔径向瓦斯渗流特性。（5）首次采用光纤光栅技术测试了不同水力冲煤孔径钻孔周围煤体径向变形规律，提出了通过径向膨胀变形量指标分析钻孔卸压效果。现场测试表明，采取水力冲煤措施10d后，距钻孔中心1.35m~4.35m处煤体膨胀变形量为40.47‰~1.92‰，煤体孔径由原来的160mm增加至579mm，钻孔卸压半径扩大了1.71m。青东煤矿水力化钻孔区域防突技术现场试验表明，采用该技术后，煤体透气性系数提高61.1~144.7倍，掘进工作面前方应力集中区移向深部，应力集中系数降低，钻屑瓦斯解吸指标均显著降低，区域防突效果显著。更多还原

【Abstract】 For controlling the coal and gas outburst of a single coal seam with low gaspermeability, variety of hydraulic drillings such as hydraulic punching, water injectionand hydraulic fracturing etc. were developed. However, the mechanism of moistureeffecting on characteristics of Coalbed Gas Seepage (CGS) in gassy coal is still lackof in-depth study. In this paper, the properties of Gas Radial Seepage Around theHydraulic Drill of (GRSAHD) were studied by laboratory tests, numerical simulation,field tests and application. The results are as follows.The experimental set-up of the GRSAHD was developed. Experiments of radialsteady/unsteady flow, water injection and gas dispersing, isothermal adsorption ofcoal with wetting and high-pressure water injection can be conducted. Meantime, thisequipment can meet the experimental conditions of different overburden pressure, gasseepage pressure, gas type, borehole diameter and the moisture content, as well asmonitor the water inlet pressure and boundary pressure under different flow.Gas pressure, adsorption, overburden pressure and the influence of drilling reliefon coal permeability were researched based on steady radial-seepage-experiment.Kinetic processes of water injection and gas dispersing were analyzed. Inner and outerboundary pressure evolution during the water injection and gas dispersing were tested.Four stages of water injection and gas dispersing were raised. Overburden pressure,raw gas pressure, water flow and other factors on the coal seam gas seepagecharacteristics of water injection and gas dispersing were researched. In addition, themoisture content distribution of coal around the borehole was also obtained.The physical model of GRSAHD was raised. In this model, coal isothermaladsorption characteristics and pore characteristics affected by the moisture werestudied. The influence of water/CH4competitive adsorption on the permeability ofcoal was tested. Laboratory determination of coal seam gas permeability affected bythe moisture was established. Finally, the prediction model of CH4permeability in wetcoal was built and verified by experiments.Distribution of radial flow field around borehole under different pre-pumpingtime, borehole diameter, original gas pressure and permeability model was simulated,which also verified the GRSAHD.For the first time, the radial deformation of hydraulic drilling with differentborehole diameter was measured by the FBG technology. The deformation of radialexpansion was used as the indicator for evaluating the effect of drilling relief. The field test shows that expansion of deformation of coal which away from the center ofdrilling1.35m~4.35m is40.47‰~1.92‰. The diameter of coal increases from160mm to579mm. The diameter of drilling relief increases by1.71m. The fieldexperiment of regional outburst prevention technology by hydraulic drillings inQINGDONG coal mine suggested that the coal permeability coefficient increased61.1~144.7times after treated by this method. In the heading face, the stressconcentration is moving to the deep, stress concentration factor is reducing, and thegas desorption index is significantly lower. The effect of Regional outburst preventionis remarkable.更多还原