The conventional methods of laboratory permeability test may not be appropriate for soft rock. In this paper, an apparatus was developed for determining rock permeability using flow-pump approach and allowing for the control over the specimen confining pressure and saturation. Results from the flow-pump permeability tests verify the capability of this apparatus which is specially designed for soft rocks. The presented work shows that the permeability of soft rock considerably depends on the subjected confining pressure and loading history. The permeability anisotropy of a soft rock was also explored by testing specimens prepared along different orientations. Besides the permeability tests, the effect of seepage on the microstructure of poorly cemented sandstone were investigated by examining the microscopic features of the tested rock material using sectioned specimens obtained before and after the seepage flow. The objective is to investigate the possible degradation due to seepage. By comparing the microstructure before and after seepage, it was found that the porosity of the rock material increases and results in degradation. Its reason is probably due to that fines particles or infill materials were moved away as a result of internal erosion along with seepage flow. On the other hand, other major texture parameters (including grain area, equivalent diameter, major axis angle, elongation, and roundness) are not affected by seepage.
- Permeability apparatus
- Soft rock