“…Concurrent with instrument development, numerous theoretical, empirical, and field studies have demonstrated robust correlations between the measured NMR response and key hydraulic parameters including fluid‐filled porosity (Timur, ), pore size distribution (Gallegos & Smith, ), permeability (Kenyon, Day, Straley, & Willemsen, ; Seevers, ; Shikhov, d'Eurydice, Arns, & Arns, ), and a number of researchers have presented specific applications in unconsolidated media, including both the saturated and vadose zones (e.g., Behroozmand, Keating, & Auken, ; Costabel & Günther, 2014; Costabel & Yaramanci, ; Dlubac et al., ; Falzone & Keating, ; Keating & Falzone, ; Kirkland & Codd, ; Knight et al., ; Merz, Pohlmeier, Vanderborght, Van Dusschoten, & Vereecken, ; Parsekian et al., ). The physical principle of NMR logging is the same principle underlying magnetic resonance imaging technology used in medicine and NMR spectroscopy in chemistry; specifically, NMR methods utilize a quantum physical property associated with hydrogen atoms known as the nuclear spin angular momentum, where the NMR tool measures the response of the hydrogen spins to a magnetic field perturbation (Dunn, Bergman, & Latorraca, ).…”