Figure 9.
Panel a shows a graph of diffusion versus permeability, with increasing trend from about 1.0 into 10 power minus 10 to about 1.0 into 10 power minus 9 as permeability increases from about 1.0 into 10 power minus 19 to about 1.0 into 10 power minus 15. Panel b shows a graph of diffusion versus clay content, with slight increasing trend from about 3.0 into 10 power minus 10 to about 4.0 into 10 power minus 10 as clay content increases from about 20 to 60 per cent. Panel c shows a graph of diffusion versus silt content, with weak increasing trend from about 2.5 into 10 power minus 10 to about 5.0 into 10 power minus 10 as silt content increases from about 10 to 50 per cent. Panel d shows a graph of diffusion versus sand content, with decreasing trend from about 5.0 into 10 power minus 10 to about 2.0 into 10 power minus 10 as sand content increases from about 20 to 70 per cent. Panel e shows a graph of diffusion versus surface area, with slight increasing trend from about 2.5 into 10 power minus 10 to about 4.0 into 10 power minus 10 as surface area increases from about 200 to 450 square metres per second. Panel f shows a graph of diffusion versus bulk density, with decreasing trend from about 6.5 into 10 power minus 10 to about 2.5 into 10 power minus 10 as bulk density increases from about 1700 to 2100 kilograms per cubic metre.Diffusivity plotted for natural and synthetic materials against permeability (a); clay, silt, and sand contents (b–d), surface area measured using EGME (e) and bulk density (f). The trend lines show linear regression fits to the data and are calculated without inclusion of the Eigenbilzen Sands (except in graph (a) and (f)). In the absence of XRD data for BC3, the data from BC2 taken from the same core barrel was used in (b–e)