f INTERPRETING NUCLEAR MAGNETIC RESONANCE RELAXATION MEASUREMENTS IN UNSATURATED POROUS MEDIA

Near-surface geophysical applications of nuclear magnetic resonance (NMR) have primarily focused on interpreting NMR measurements under the assumption that the measured volume is fully saturated; however, as NMR is used for a wider set of near surface applications, an improved understanding of NMR measurements of unsaturated porous media will be needed. Our research focuses on using laboratory measurements to understand the relationship between the NMR relaxation time (T- 2) and the water content of unsaturated porous geologic material. A limited number of recent studies have determined how the shape and magnitude of the T2-water content relationship varies with the surface-area-to-volume ratio (S/V) of a porous media. Although it is well known that in fully-saturated porous material T2 is affected by the surface relaxivity (a parameter that quantifies the ability of a pore surface to enhance relaxation) as well as S/V, there have been no studies that explore the effect of surface relaxivity on the T2-water content relationship. We will present results from a laboratory study designed to understand the effect of both surface relaxivity and S/V on the T2-water content relationship.