Patent ID: 8384379

Claim:
A method of determining material properties within a portion of a fluid-containing porous medium, the porous medium being part of a subterranean formation, the method comprising: a) injecting acoustic energy into the portion of the porous medium; b) generating a magnetic field gradient within the portion of the porous medium; c) injecting a radio frequency energy into the portion of the porous medium; wherein the acoustic energy, the magnetic field gradient, and radio frequency energy have a predetermined relationship in time; d) measuring an NMR signal from the portion of the porous medium; e) repeating a), b), c), and d) for one or more different values of the magnetic field gradient; f) processing the measured NMR signals to determine at least one material property of the porous medium, wherein the at least one material property comprises a pore fluid velocity distribution; and g) determining a relative pore size distribution from the pore fluid velocity distribution.