Permeability determination of a deep argillite in saturated and partially saturated conditions

This paper deals with the methods of determination of permeability in saturated and partially saturated conditions for low permeable porous rocks such as argillites. The modified version of the pulse test proposed by Hsieh et al. [Int. J. Rock Mech. Min. Sci. Geomech. Abstr. 18 (1981) 245] has been used to characterize permeability in the saturated case. It enables the hydraulic diffusivity and then the intrinsic permeability and the specific storage coefficient to be characterized. In partially saturated conditions the method of saline solution to impose relative humidity and then capillary pressure has been used. The permeability in the partially saturated range can be deduced form measurements of transient weight loss and deformations of a sample submitted to a decrease of relative humidity in an hermetic chamber. In the two cases, pulse and drying tests, original experimental devices have been developed. The parameter-identification procedure based on the solution of corresponding inverse problems is presented. First approach explicit or semi-explicit solutions for the direct problems are used. It shows that the simplified linear approach is useful to obtain correct order of magnitude of unknowns parameters.