砂岩与砂质泥岩渗透性能试验研究

Testing Study on Permeability of Sandstone and Sandy Mudstone

利用柔性壁渗透仪对取自兰州地区的砂岩和砂质泥岩试样进行了渗透性能的试验研究,通过施加不同围压和渗透压,比较砂岩与砂质泥岩两者的渗透性能,并根据试验数据对渗透系数与渗透压进行拟合,同时,利用扫描电镜(SEM)对渗透前后的砂岩和砂质泥岩进行微观分析。试验结果表明:在200 k Pa围压时,渗透系数随渗透压增加有增长趋势,在300k Pa、400 k Pa围压时,渗透系数随渗透压增加先增大后保持稳定;在同等围压和渗透压下,砂质泥岩的渗透系数要大于砂岩;根据物理力学性质指标,可通过岩石吸水率和孔隙率对渗透系数进行判定。通过观察电镜结果可知,渗透试验前后,两者内部结构变化较大。

A flexible wall permeameter was used to test permeability of sandstone and sandy mudstone samples taken from Lanzhou. Permeability of sandstone and sandy mudstone was compared by applying different confining pressures and seepage pressures. The relationship between permeability coefficient and seepage pressure was fitted according to test data. Using SEM to analysis the microscopic of sandstone and sandy mudstone before and after penetrant test. The results show that under the confining pressure of 200kPa,with increasing of seepage pressure,the permeability coefficient maintains a growth trend; while under the confining pressure of 300kPa and 400kPa,with the increasing of seepage pressure,the permeability coefficient increases first and then remains stable. Under the same confining pressure and seepage pressure,permeability coefficient of sandy mudstone is greater than that of sandstone; The permeability can be determined by water absorption and porosity of rock according to physical and mechanical properties index. The results of SEM show that before and after the penetrant test,sandstone and sandy mudstone both have bigger change in internal structure.