Fluids and Rocks - Introduction to Carbon Capture and Sequestration - page 446

Figure 9.8.8 SEM reconstruction of the mineralogy and connected porosity of a sand-
stone sample
Scanning electron microscopy (SEM) images of a sandstone sample from the Cranfi eld
CO 2 sequestration pilot site in Mississippi (6 by 2.4 mm area) with pore space and min-
eralogy identifi ed by electron microscopy and X-ray spectroscopy techniques. In the
upper image, where mineralogy is mapped with a resolution of 1 µ m, most of the pore
space appears to be unconnected (in black). In the lower image, where mineralogy is
mapped with a fi ner resolution (0.33 µ m) and the chlorite mineral fraction (in blue) is
treated as a phase with well-connected internal nanoporosity (as revealed by nanoto-
mography experiments), most of the pore space is seen to be connected (in white). The
fi gure shows that the more fi nely one looks at a rock sample, the more pores appear to
be connected. This type of very fi ne-scale characterizations becomes extremely chal-
lenging if one wishes to apply it to a large enough region of the rock sample to capture
the heterogeneity of the rock on scales of centimeters or more. Images reproduced from
Landrot et al. [9.41], with permission from Elsevier .