In situ gas and brine permeability measurements in salt

The results of a field experiment carried out in a salt layer in the Mines de Potasse d'Alsace (France) confirm that rock salt is permeable to gas and to brine, at least around underground facilities. A simple analysis of measured gas flow rate shows that (a) capillary pressure effect is significant (b) fluid migration in salt is not controlled by Darcy diffusion. The results of the tests with brine are interpreted in a satisfactory way using a model based on Darcy's law characterized by a permeability value of 2.10 -21 m 2 and an initial pore pressure value of 1 MPa. The following non linear effects are considered : (1) salt damage created by borehole drilling (2) effective stress changes (3) change in salt concentration of brine saturation state resulting from pressure changes.