The H1 Nuclear Magnetic Resonance Spin-Lattice Relaxation Rate of Some Hydrated Synthetic and Natural Sands

Abstract

The hydrogen nuclear magnetic resonance (NMR) spin-lattice relaxation rate [Formula: see text] of three fully hydrated natural sands was measured and compared to that for a fully hydrated synthetic sand as a function of applied magnetic field and particle diameter [Formula: see text]. [Formula: see text] values increased with decreasing particle diameter for both natural and synthetic sands. The increase in [Formula: see text] became greater with decreasing magnetic field strength. The field dependent [Formula: see text] data allowed the prediction of [Formula: see text] at the Earth’s magnetic field [Formula: see text]. Measurable [Formula: see text] differences were observed between the three natural sands, as well as the natural and a synthetic sand. The difference in [Formula: see text] of the natural sands can not be attributed to the geometric characteristics of the grains, as these were identical within experimental error. The [Formula: see text] differences can be attributed to trace paramagnetic impurities in the grains which influence the surface relaxation component of [Formula: see text]. These results show that it is unwise to predict aquifer characteristics based on [Formula: see text] values from nuclear magnetic resonance sounding without knowledge of the paramagnetic impurities in the sand grains. Furthermore, the results emphasize that laboratory measurements of [Formula: see text] should be performed at [Formula: see text].