PORE-LEVEL VALIDATION OF REPRESENTATIVE PORE NETWORKS OBTAINED FROM MICRO-CT IMAGES

We test the accuracy of pore network models generated from microtomographic images by comparing computations of permeability and wetting fluid continuity based on the images and network models extracted from the images. The comparisons are made for three rock-types including two clastic rocks (consolidated and unconsolidated) and one outcrop carbonate. We describe the network extraction procedure and note the non-unique aspects of the resultant networks and the effect which this has on predictions of permeability. Permeabilities are found to be in very good agreement for large image volumes (>10,000 pores). At a local scale we compare the flow rates within individual pores for the image based computations with those for the network. Whilst there is considerable scatter in the data, the overall trends are similar. We also question the merits of the usual network model assumptions that every pore and throat in the network has a uniform cross-sectional shape, determined from an equivalent shape factor, and that corner wetting fluid remain continuous throughout the network. An image based investigation of the connectivity of the crevice wetting phase shows that corner wetting phase becomes increasingly disconnected as the wetting phase saturation is reduced