Quantitative image analysis of finite porous media

Abstract

SUMMARYReconstruction, from serial sections, of a branch‐node chart containing the connection pattern of the pore channels in small sandstone samples, and computation of genus are described.Seventy‐eight serial sections were obtained by serially grinding off layers of about 10 μm thickness from a 1 × 1 mm sample, whose pores had been filled with Wood's metal, and taking photomicrographs of the polished sections. Edge effects and rock enclosed by pore space were accounted for in the construction of the branch‐node chart. The importance of boundary effects was reflected by the difference between the minimum and maximum estimates of genus, Gmin and Gmax, respectively.The Berea sample (with porosity of 23% and average grain size of about 200 μm) was found to have essentially one main network containing over 87% of all pore space features, plus a number of very much smaller boundary networks representing ‘dents' on the sample sides. The number of anomalies from missed connections was found to be small and unlikely to cause significant error in the genus calculations. Both Gmin and Gmax for the sample were found to be essentially those of the one continuous main network.