  Formation evaluation of unconventional reservoirs is challenging due to the
coexistence of different phases such as kerogen, bitumen, movable and bound
light hydrocarbon and water. Current low-frequency (0.05 T) nuclear magnetic
resonance (NMR) laboratory and logging methods are incapable of quantitatively
separating the different phases. We demonstrate the utility of high-field (9 T)
NMR 2D T1-T2 measurements for separating hydrocarbon and the clay-interacting
aqueous phases in shale based on the difference in the frequency dependence of
the spin-lattice relaxation time. Furthermore, we demonstrate 23Na NMR as a
promising complementary technique to conventional 1H NMR for shale fluid
typing, taking advantage of the fact that sodium ions are only present in the
aqueous phase. We validate high-field (9 T) 23Na-1H NMR relaxometry for
assessing brine-filled porosity and brine salinity in various porous materials,
including porous glass, conventional rocks, clays, and shale, and apply it for
differentiating hydrocarbon versus aqueous components and also the
clay-associated versus free water in Eagle Ford shale cores. This work lays the
groundwork for developing future downhole 23Na-1H NMR logging techniques.
