低渗透岩石渗透率与孔隙率演化规律的气渗试验研究

摘要

The low-permeability rock is the main material and geological environment for storing under⁃ ground oil and gas, CO2 and radioactive waste, and also a complex media usual using in water resource and hydropower. In this study, based on the gas permeability and porosity test system jointly developed by the Rock Mechanics Laboratory of Geotechnical Research Institute of Hohai University of China and Lille University of Science and Technology of France, using the inert gas of argon as the fluid medium, the stress-dependent permeability and porosity of (weathering) granite and monzonitic granite are measured, the change of porosity and permeability with the confining pressure and the function relationship between porosi⁃ ty and permeability are analyzed and discussed. The test results show that, for the low-permeability rock, the porosity and permeability exponential decrease with the increase of confining pressure, the BSE micro⁃ structure images of tested rock sample also illustrates the relationship between the confining pressure and the structure of rock;when the particle crushing mechanism is not involved in the evolution of the permea⁃ bility, a power law can better describe the relationship among the permeability and porosity of the test rock specimens.%低渗透岩石是地下石油和天然气储存、CO2储存、核废料处置的主要介质和地质环境，也是水利水电等工程建设中常见的一种复杂介质。利用河海大学与法国国家科研中心里尔力学研究所共同研发的低渗透岩石惰性气体渗透试验系统，以氩气为渗透介质，测试了3种低渗透岩石在不同围压作用下的有效孔隙率和气体渗透率的变化规律，分析和讨论了孔隙率和渗透率随围压的变化关系以及孔隙率与渗透率之间的函数关系。试验结果表明，对低渗透岩石，随着围压的增大，孔隙率和渗透率呈指数函数关系递减，试样BSE微观结构图像结果也表明了围压与孔隙结构的相关关系；在不考虑孔隙坍塌效应时，渗透率与孔隙率之间符合幂函数关系。