Figure 5 a,b.  Microporous grains and microporous matrix in Arab Formation carbonates. In thin section, porosity is filled by blue-dyed epoxy, calcite is stained pink to red, other minerals are unstained. (a) Epoxy pore cast of microporous ooid. Note radial and concentric distribution of porosity in ooid cortex (arrows) (SEM image, Saudi Arabia, Berri field, Arab-A). (b) Higher magnification view of epoxy pore cast of same microporous ooid shown in previous example. Again, microporosity consists of a maze of highly interconnected pore throats (arrows) and larger, more equant micropores (MC). Pore network of micritized grain (Figure 3e), foraminifer (Figure 4f) and ooid are essentially identical.