Porous media with open porosity are three-dimensional (3D) structures, often consisting of a complex network of pores connected by throats. The morphology and connectivity of the pore space in porous media are commonly characterized by the pore and throat size distributions, the mean pore-throat aspect ratio and the mean connectivity number, i.e. the number of connections (throats) to each pore. These parameters can be estimated from two-dimensional images (slices) of porous materials and are often applied to correlate the properties of the pore space to its ability to trap a non-wetting phase such as air, oil, or CO2 in geological carbon sequestration. These parameters, i.e. the size distributions, aspect ratio and connectivity number, however, rarely describe the true 3D characteristics and connectivity of the pore space. Additional parameters quantifying the 3D connectivity of the pore space are therefore required to characterize porous media and to improve predictions of non-wetting trapping.
In the work presented here, we characterized the pore space of various porous media using two novel ‘connectivity parameters’, in addition to the traditional parameters mentioned above. These parameters were: the second geobody connectivity metric, related to percolation theory; and, the topology of the pore space, as described by the Euler number. We compared the ability of columns of partially sintered glass particles to trap a non-wetting phase (air) and related this ability to both the traditional and novel parameters. All pore space parameters were calculated from 3D images of porous media collected with X-ray computed tomography.
This talk will also touch upon results from our recently published research, related to geological carbon sequestration, where we used these novel connectivity parameters to describe the flow process of different fluid pairs (air and brine; and, supercritical CO2 and brine) as well as the pore-scale response of the porous media.