Pore structure characterization in rock salt

The pore space of rock salt from the Lower Salt Unit of the Cardona Saline Fm. (Spain) was characterized using three independent methods (mercury injection porosimetry, saturation in a low viscosity isoparaflin and gas adsorption). The total porosity in the studied samples ranged from 0.97 to 3.09%. Pores may be present as macropores (> 7.5 μm), micropores (between 7.5 μm and 100 nm) and infrapores (< 100 nm). The porosity is mainly associated with a well developed microporous system, which, in turn, is related to the presence of clay minerals in the rock salt. Macropores are randomly distributed throughout the rock body. They are sheet-like rather than cylindrical. The degree of connectivity of the porous network is variable. Infraporosity consists of a bundle of non-intersecting pores, whereas microporosity can be considered as a network of pores and throats. Macro and micropores exhibit a fractal pore-surface structure, whereas infrapores have a non-fractal (Euclidean) structure.