Figure 22. Representative photomicrographs and SEM images.

Photomicrograph (plane light) and SEM image from the upper unit of the Navajo Sandstone showing typical well-sorted, subangular to subrounded quartz sand and silt. Note a few fractured and corroded K-feldspar grains are present. Blue space on photomicrograph is intergranular porosity. Federal No. 17-2 well, 6129 ft, porosity = 8.1%, permeability = 17.9 mD.

Photomicrograph (plane light) and SEM image from the lower unit of the Navajo Sandstone showing bimodal distribution of subangular to subrounded quartz sand and silt. Blue space on photomicrograph is intergranular porosity. Federal No. 17-3 well, 6773 ft, porosity = 14.8%, permeability = 149 mD