Permeability of dried and re-saturated shaly samples and accompanying microstructural changes

Abstract

© 2016 SEG.Permeability that is of practical importance for both reservoir rocks and seals is often measured in laboratory as in situ borehole measurements are expensive and timeconsuming. A practice of permeability measurements on dry samples, which is common in oil and gas industry, frequently gives results that strongly overestimate permeability measured on water-saturated samples. In this study permeability to gas and to brine were measured on shaly samples with high fraction of swelling clays. Microstructural changes, which accompanying the resaturation process, were photographed using micro computed tomography. We found that significant difference in gas and brine permeability is caused by shrinkage of swelling clay that results in crack opening. As this process is irreversible, any efforts to resolve the true permeability depend on avoiding desiccation of the core samples with swelling clays.