NMR IMAGING OF WATER IN MODEL POROUS MATERIALS

Nuclear magnetic resonance images have been obtained for four porous glass disks of different porosities as models of materials such as oil cores. The mottled appearance often seen for such images is attributed largely to insufficient signal-to-noise ratio, and not pore structures. Comparison of spin-echo and gradient-echo images demonstrates the defect-magnification effect of the gradient-echo sequence seen previously for elastomers. The advantages of volume imaging, isotropic voxels in thin slices, and higher resolution are demonstrated for porous materials. Images with isotropic voxels of 80 to 100-mu-m on a side were obtained in several hours. Dramatic differences are not seen at 100-mu-m resolution for disks of average pore size 15 to 200-mu-m because the images are dominated by the large-pore tail of the size distribution.