标题：Simulating permeability reduction by clay mineral nanopores in a tight sandstone by combining computer X-ray microtomography and focussed ion beam scanning electron microscopy imaging
摘要：Computer X-ray microtomography (µXCT) represents a powerful tool forinvestigating the physical properties of porous rocks. While calculatedporosities determined by this method typically match experimentalmeasurements, computed permeabilities are often overestimated by more than1 order of magnitude. This effect increases towards smaller pore sizes, asshown in this study, in which nanostructural features related to clayminerals reduce the permeability of tight reservoir sandstone samples.Focussed ion beam scanningelectron microscopy (FIB-SEM) tomography was applied to determine the permeability effects ofillites at the nanometre scale, and Navier–Stokes equations were applied tocalculate the permeability of these domains. With these data, microporousdomains (porous voxels) were defined using microtomography images of a tightreservoir sample. The distribution of these domains could be extrapolated bycalibration against size distributions measured in FIB-SEM images. For this,we assumed a mean permeability for the dominant clay mineral (illite) in therock and assigned it to the microporous domains within the structure. Theresults prove the applicability of our novel approach by combining FIB-SEMwith X-ray tomographic rock core scans to achieve a good correspondencebetween measured and simulated permeabilities. This methodology results in amore accurate representation of reservoir rock permeability in comparison tothat estimated purely based on µXCT images.
