Experimental measurement of permeability evolution in sandstone during hydrostatic compaction and triaxial deformation

摘要

The permeability of sandstone during hydrostatic compaction and triaxial deformation was measured using a rock triaxial servo-controlled system. The gas permeability was also measured using an integrated permeability and porosity test system to study the difference between gas and water permeability. The experimental results suggested that gas permeability is larger than water permeability by almost one order of magnitude. This phenomenon is due to the slippage effect. The modified permeability is much closer to the water permeability. An empirical exponential relationship can describe the stress-dependent permeability of sandstone, while a power law is suitable to describe the relationship between porosity and effective confining pressure. During triaxial deformation, permeability initially decreases and then begins to increase at an accelerating rate. The peak value of permeability is hysteretic to peak stress. The initial permeability, lowest permeability, peak permeability, and stable value of permeability all decrease with the increase of effective confining pressure. The volumetric strain has a great effect on permeability. The turning point where permeability starts to increase coincides well with the onset of dilatancy.