摘要
针对浅埋隧道穿越高瓦斯地层治理效果不理想、施工风险高的问题,基于流体多孔介质理论,将煤层瓦斯驱替抽采技术应用于高瓦斯地层浅埋隧道施工治理。采用理论分析、数值模拟的方法分析了地层瓦斯驱替的性能,确定了瓦斯驱替影响范围、瓦斯驱替时间,对可能影响驱替性能的抽排负压、注气压力、地层渗透率、钻孔孔径4个因素进行研究,最后通过现场实验对地层瓦斯驱替数值模拟结果进行论证。结果表明:在抽排负压PC=50 kPa和注气压力P_(Z)=2.0 MPa条件下,注气、抽排孔间距12 m时采用注气40 min,同时抽排90 min达到的驱替效果较好;抽排负压越小驱替性能越好,但抽排负压对驱替进程影响较小;注气压力的提高能显著提高瓦斯抽排量、减少驱替时间;地层瓦斯下降量、抽排孔瓦斯流量与渗透率有着近线性的正相关性;对于目前常用钻孔孔径来说,增大钻孔孔径对地层瓦斯驱替治理效果影响不明显;由于地层条件、设备限制、施工扰动等因素,现场实验与数值模拟瓦斯含量监测数据存在一定差异,但两者在驱替效果和时间进程上具有较高的吻合度。
In response to the unsatisfactory treatment effect and high construction risk of shallow buried tunnels crossing high gas formations,based on the theory of fluid porous media,the coal seam gas displacement and extraction technology is applied to the construction treatment of shallow buried tunnels in high gas formations.The performance of gas displacement in the formation was analyzed using theoretical analysis and numerical simulation methods.The influence range and time of gas displacement were determined.Four factors that may affect displacement performance,including negative pressure of drainage,gas injection pressure,formation permeability,and borehole diameter,were studied.Finally,the numerical simulation results of gas displacement in the formation were demonstrated through on-site experiments.The results show that under the condition of negative pressure P C=50 kPa and injection pressure P_(Z)=2.0 MPa,when the distance between injection and extraction holes is 12 m,gas injection for 40 min is used,and the displacement effect achieved by pumping for 90 min is better.The smaller the suction negative pressure,the better the displacement performance,but the impact of suction negative pressure on the displacement process is relatively small;The increase of gas injection pressure can significantly increase gas drainage capacity and reduce displacement time;There is a nearly linear positive correlation between the decrease in formation gas,gas flow rate from drainage holes,and permeability;For the commonly used borehole diameter,increasing the borehole diameter has little effect on the effectiveness of gas displacement control in the formation.Due to factors such as geological conditions,equipment limitations,and construction disturbances,there are certain differences between on-site experiments and numerical simulations of gas content monitoring data.However,the two have a high degree of consistency in terms of displacement effect and time progress.
作者
苏培东
石疏桐
李有贵
Su Peidong;Shi Shutong;Li Yougui(School of Geoscience and Technology,Southwest Petroleum University,Chengdu 610500,P.R.China)
出处
《地下空间与工程学报》
北大核心
2025年第6期2203-2216,共14页
Chinese Journal of Underground Space and Engineering
关键词
浅埋隧道
瓦斯隧道
瓦斯驱替
数值模拟
现场实验
shallow buried tunnels
gas tunnels
gas displacement
numerical simulation
on-site experiments
