低渗透介质温度–应力–渗流耦合三轴仪研制及其应用

DEVELOPMENT OF THERMO-GASEOUS-MECHANICAL COUPLING TRIAXIAL TESTING SYSTEM OF LOW PERMEABILITY MEDIUM AND ITS APPLICATION

详细介绍研制的低渗透介质温度–应力–渗流耦合三轴仪,该试验系统可以在常温～90℃范围、三轴室活塞最大轴向力1000kN、围压40MPa内对直径50和100mm的标准试样进行轴向和径向渗透试验。解决长时间、高温(<90℃)条件下试样气体渗透密封性、微流量气体体积量测以及长时间试验温度保持均匀、恒定等技术问题,确保复杂条件下低渗透介质渗透性测试。应用研制的三轴仪,对雅砻江锦屏II级电站辅助洞白山组大理岩进行渗透性测试。试验结果表明:研制的三轴仪可以满足温度–应力–渗流耦合试验的要求,试验过程稳定、试验数据精度较高,可用于石油/天然气地下能源储存、低渗透油气田开发、高瓦斯矿井瓦斯抽放、放射性废料地质深埋处置等工程中围岩介质渗透特性研究,可为工程安全和环境评估提供基本参数。

A new thermo-gaseous-mechanical coupling laboratory apparatus measuring rock properties is developed and used to measure gas flow rate for two different specimen sizes of 50 mm and 100 mm in diameter. Either axial or radial permeability way can investigate gas transport properties in rocks. The maximum test temperature is 90 ℃, the maximum axial force of triaxial piston can be 1 000 kN and the maximum confining pressure is 40 MPa. Difficult techniques for permeability test of low permeability medium such as long testing time（lasting one week）, sample sealing performance under high temperature（less than 90 ℃）, accuracy of micro-flow measuring, uniformity and constancy of testing temperature during test are solved. Tests are carried out on dense marble samples taken from Jinping II hydropower station. Test results show that the apparatus can satisfy the requirement for thermo-gaseous-mechanical coupling test for low permeability medium. Using this equipment, transport parameters of surrounding rock are available for environment evaluation and steady analysis in important projects such as oil/gas storage in depth, oil/gas exploitation in low permeability oil/gas field, gas drainage in gas mine and geological disposal of high radioactive waste.