112-7 Applications of Nuclear Magnetic Resonance for Hydrogeologic Characterization in a Sand and Silt Column

Session: Geophysics in Investigating and Exploring for Mineral, Energy and Groundwater Resources (Posters)

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Geophysical techniques offer a non-invasive, in situ approach for investigating subsurface geological conditions and present a practical alternative to borehole drilling. Among a variety of widely used geophysical methods such as seismic, electrical resistivity, and ground-penetrating radar, nuclear magnetic resonance (NMR) stands out as it directly measures the responses of water molecules (hydrogen atoms) to magnetic perturbations. Those responses can be used to estimate water contents (both mobile and immobile) and hydraulic conductivity, making NMR valuable for groundwater investigations. Given the increasing interest in NMR, evaluating the high-resolution application of the technique is critical for understanding how it can be used to identify different geologic materials with varying hydraulic conductivities. This study investigated how the vertical advancement interval during NMR profiling affects the utility of NMR data for detecting different layers of geologic materials. A laboratory column consisting of 10 ft and 3 layers of sand and silt was constructed. The column was logged by an NMR tool (Dart manufactured by Vista Clara) at intervals of 0.05 ft, 0.15 ft, and 0.5 ft. The results, interpreted using the Schlumberger-Doll Research (SDR) equation, showed that the 0.05 ft logging interval had the highest resolution, enabling clearer detection of geologic material contacts. In contrast, the 0.5 ft logging interval produced a coarser resolution and limited ability to distinguish between contrasting materials. Ultimately, reducing the logging interval enhanced the data resolution and improved the technique's ability to detect contrast between materials of different hydraulic properties.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-9485

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