Successful Sampling Strategy Advances Laboratory Studies of NMR Logging in Unconsolidated Aquifers

The nuclear magnetic resonance (NMR) technique has become popular in groundwater studies because it responds directly to the presence and mobility of water in a porous medium. There is a need to conduct laboratory experiments to aid in the development of NMR hydraulic conductivity models, as is typically done in the petroleum industry. However, the challenge has been obtaining high‐quality laboratory samples from unconsolidated aquifers. At a study site in Denmark, we employed sonic drilling, which minimizes the disturbance of the surrounding material, and extracted twelve 7.6 cm diameter samples for laboratory measurements. We present a detailed comparison of the acquired laboratory and logging NMR data. The agreement observed between the laboratory and logging data suggests that the methodologies proposed in this study provide good conditions for studying NMR measurements of unconsolidated near‐surface aquifers. Finally, we show how laboratory sample size and condition impact the NMR measurements. Key Points First detailed comparison of laboratory and logging NMR estimated parameters in unconsolidated aquifers Proposing drilling and sampling methodologies to overcome the challenges facing laboratory and logging NMR measurements in unconsolidated aquifers The methods employed in this study support the use of laboratory NMR to develop the interpretation of NMR logging for aquifer characterization