PROBING SOIL AND AQUIFER MATERIAL POROSITY WITH NUCLEAR-MAGNETIC-RESONANCE

Nuclear magnetic resonance relaxation measurements were used to identi fy different characteristic porosity domains in soil and aquifer mater ials. The porosity distribution can be inferred from these measurement s by a regularization method applicable to any nuclear magnetic resona nce (NMR) relaxation, or by an analytic method applicable only to mult iexponential relaxations (D'Orazio et al., 1989). The porosity distrib ution obtained from NMR relaxation measurements strongly depends on th e pore shape factor. For the Borden aquifer material, both the regular ized and the analytic pore size distribution obtained from NMR relaxat ion measurements are consistent with those obtained by Ball et al. (19 90) using Hg porosimetry and N2 adsorption. For the Eustis and the Web ster soils, the measured porosity domains are qualitatively consistent with those expected based on their respective composition. Our findin gs suggest that due to the long time required to saturate fine pores, NMR measurements of porosity distribution that are collected at short saturation times are biased toward larger pore sizes.