Capillary Pressure Determination from Sorption Isotherms for Mixtures of Porous Solids

Abstract

Capillary pressure and relative permeability are important parameters for characterization of the draining of fluid phases in porous media. In this work, capillary pressure and relative permeability were evaluated in porous solids with distinct morphological properties, namely NaY zeolite, kaolin, and alumina as well as their binary mixtures in the compositions of 20, 40, 60, and 80% in mass fraction. The objective of the present work was to verify the influence of the composition of the solid mixture and the structural characteristics of the components on capillary pressure and relative permeability. Capillary pressure as a function of saturation of the material was determined from moisture desorption isotherms. The results showed that structural characteristics greatly influence capillary pressure and permeability. The obtained capillary pressure in microporous materials was higher than that in macroporous and mesoporosous materials at the same saturation. It was verified that when microporous materials were present in the mixture, the capillary pressure of the binary mixtures tended to approach the capillary pressure of the microporous materials, since micropores control the adsorption and desorption processes.

Keywords:

• Porous media
• Solid mixtures
• Permeability
• Kaolin
• NaY Zeolite
• Alumina

The authors acknowledge CNPq (National Research Council of Brazil) for the Doctor's Degree scholarship of M.N.N. Miranda.