  In this work, we present a characterization of phase configuration in
water-saturated sintered glass bead samples after oil injection, through the
analysis of time-dependent diffusion coefficients obtained from sets of
one-dimensional pulsed field gradient nuclear magnetic resonance (PFG NMR)
measurements, pre and post drainage. Estimates of samples surface-to-volume
ratio and permeability from pre drainage PFG measurements in a water-saturated
sample were compared with analytical and reported values, respectively, and a
fair agreement was found in both cases. Short-time analysis of diffusion
coefficients extracted from PFG measurements was used to quantify the increase
in surface-to-volume ratio probed by the wetting phase after drainage. Analysis
of water and oil diffusion coefficients from post drainage PFG experiments were
carried out using a bi-Gaussian model, and two distinct scenarios were
considered to describe fluids conformation within pores. For the case where
non-wetting phase was considered to exhibit a poorly connected geometry, an
analysis assuming the formation of oi-in-water droplets within pores was
performed, and a Gaussian distribution of droplets radii was determined.
