摘要
松软低渗透高瓦斯煤层瓦斯抽采是矿井瓦斯抽采的难点,该类煤层极低的渗透性是地应力和高瓦斯压力长期共同作用的结果。为研究地应力和气体压力长期作用对煤层渗透性的影响,采用岩石三轴渗流仪研究了山西典型焦煤在三轴应力及氮气孔隙压力长期作用下的渗流特性。结果表明:在400m埋深地层应力(轴压、围压均为10MPa)和氮气孔隙压力(6 MPa)长期作用下,焦煤原始渗透率为10-17~10-21 m2,低于10-14~10-16 m2,为低渗煤层;但初始渗透存在一临界值:约为2.0×10-19 m2。初始渗透率高于2.0×10-19 m2,焦煤渗透率先增加后降低,而后趋于平稳,平稳后的渗透率低于初始渗透率;初始渗透率低于2.0×10-19 m2焦煤渗透率呈抛物线式减少,后趋于平稳;试验后试样明显破碎,可见宏观裂缝且数量明显增多。
Gas drainage in soft coal seam with low permeability and high gas is a difficult point in mine gas drainage.The extremely low permeability of this kind of coal seam is the result of long-term joint action of in-situ stress and high gas pressure.In order to study the long-term action of in-situ stress and gas pressure on the permeability of coal seam,the permeability of typical coking coal in Shanxi under the long-term action of triaxial stress and nitrogen pore pressure was studied by rock triaxial seepage meter.The results show that,under the long-term action of stresses at 400 m buried depth(axial pressure and confining pressure both of 10 MPa)and nitrogen pore pressure(6 MPa),the original permeability of coking coal is 10-17~10-21 m2,which is lower than 10-14~10-16 m2,and this coking coal belongs to a low-permeability coal seam.There is a critical value of initial permeability,namely about 2.0×10-19 m2.When the initial permeability is higher than 2.0×10-19 m2,the permeability of coking coal firstly increases and then decreases,and then tends to be stable.The stable permeability is lower than the initial permeability.When the initial permeability is lower than 2.0×10-19 m2,the permeability of coking coal decreases parabola,and then tends to be stable;after the test,the sample is obviously broken,macroscopic cracks are visible and the number is significantly increased.
作者
杨一凡
冯子军
牛文星
万志军
YANG Yifan;FENG Zijun;NIU Wenxing;WAN Zhijun(Key Laboratory of In-situ Property-Improving Mining of Ministry of Education,Taiyuan University of Technology,Taiyuan,Shanxi 030024,China;State Key Laboratory of Coal Resources and Safe Mining,China University of Mining and Technology,Xuzhou,Jiangsu 221116,China;Department of Mining Engineering,Taiyuan University of Technology,Taiyuan,Shanxi 030024,China)
出处
《矿业研究与开发》
CAS
北大核心
2020年第7期65-69,共5页
Mining Research and Development
基金
中国矿业大学煤炭资源与安全开采国家重点实验室开放研究基金资助项目(SKLCRSM18KF015)
国家自然科学基金项目(U1810104)
山西省高等学校创新人才支持计划资助项目.
关键词
松软低渗煤层
气体吸附
渗透率
地应力
Soft coal seam with low permeability
Gas adsorption
Permeability
In-situ stress
作者简介
杨一凡(1996—),女,山西晋中人,硕士,主要从事煤层气开采研究,E-mail:229498729@qq.com;通信作者:冯子军(1983-),男,安徽阜阳人,副教授,博导,主要从事高温髙压岩石力学及原位改性采矿方面的研究,E-mail:fengzijun@tyut.edu.cn。
