EFFECTS OF HYDROSTATIC-PRESSURE ON PROTON AND DEUTERON MAGNETIC-RESONANCE OF WATER IN NATURAL ROCK AND ARTIFICIAL POROUS-MEDIA

The effect of pressure on the NMR longitudinal relaxation of D2O and H 2O confined to the interstices of natural and artificial porous media is reported. Magnetization decays of fluid protons in natural porous m edia are known to be dominated by interactions between water molecules and the surface of the solid matrix. These decays are characterized b y broad distributions of relaxation times. In some materials there is no pressure dependence of the proton relaxation time distribution, whi le in other materials minor effects are noted. The NMR relaxation of d euterium in D2O is dominated by intramolecular effects. Assuming that the enhancement of relaxation at the surface is relatively independent of surface composition, one can estimate a surface-to-pore-volume rat io. The NMR S/V is more useful than that measured by conventional meth ods. The pressure dependence of D2O relaxation in porous media follows that of the bulk liquid. (C) 1994 Academic Press, Inc.