Quantitative analysis of diffusion regimes in iron ore with low field NMR

SUMMARY The use of nuclear magnetic resonance (NMR) techniques allows in situ characterization geophysical properties such as moisture content, permeability and wettability. However, the accuracy applicability measurements is limited by internal field gradients which are a consequence susceptibility differences at solid–fluid interfaces. Such effects particularly prominent iron ore rock samples contain ferrimagnetic ferromagnetic mineralogy leading to high susceptibility. Multiple echo time Carr–Purcell–Meiboom–Gill (CPMG) NMR pulse sequences commonly used capture influence gradients, with intention deconvoluting diffusion effective (geff) from true transver relaxation (T2). interpretation complicated presence multiple diffusive regimes: short-time (ST), motionally averaged localization regimes respectively. We introduce new model for signal attenuation, called multiregime intended better behaviour across three regimes. compared against previous methods quantifying decay (the ST only generalized inversion models). Multi-echo fit each order quantify 2-D T2–geff distributions. resulting distributions demonstrate how can provide insight into relative different given sample. This assists understanding on measurement accuracy, example increased error increasing prevalence regime. provides key step accurately segregating surface relaxation, crucial estimating pore size distributions, wettability using NMR.