QUANTIFICATION OF OIL AND WATER IN PRESERVED RESERVOIR ROCK BY NMR-SPECTROSCOPY AND IMAGING

Reservoir rock analysis by proton NMR requires separation of the respo nse into brine and crude oil components. Tests on preserved core from a North Sea chalk reservoir show that spin-lattice relaxation time dis tributions can be used to distinguish the two fluids. NMR estimates of oil and water saturations for 1.5'' diameter core examined in a 10 MH z Bruker Minispec spectrometer closely match fluid contents determined by distillation. The spin-lattice relaxation contrast mechanism devel oped for core samples can be applied in the quantitative analysis of N MR images. The relaxation data are compared with data from chemical sh ift imaging on the same core sample. The results indicate that it will be possible to monitor changes in fluid distributions, in this and si milar systems, under dynamic conditions such as in a waterflood.