A BULK AND SPATIALLY-RESOLVED NMR RELAXATION STUDY OF SANDSTONE ROCK PLUGS

A detailed study of the proton nuclear magnetic-resonance spin-lattice and spin-spin relaxation time of water in a series of 10 well-charact erized sandstone rock plugs has been made as a function of saturation. The saturation levels range from 0.06%, equivalent to monolayer cover age of the surface of the pore space, to 100%. Both bulk and spatially resolved measurements have been made. The results have been used to t est fast-diffusion relaxation theory in rock over the full saturation range for the first time, Evidence has been obtained for the effect of pore throats on the relaxation rates for each plug and estimates have been made of pore-throat sizes which correlate well with water-vapor percolation thresholds. (C) 1995 Academic Press, Inc.