Glacial aquifers are an important source of groundwater in the United States and require accurate characterization to make informed management decisions. One parameter that is crucial for understanding the movement of groundwater is hydraulic conductivity, K. Nuclear magnetic resonance (NMR) logging measures the NMR response associated with the water in geological materials. By utilizing an external magnetic field to manipulate the nuclear spins associated with ¹H, the time‐varying decay of the nuclear magnetization is measured. This logging method could provide an effective way to estimate K at submeter vertical resolution, but the models that relate NMR measurements to K require calibration. At two field sites in a glacial aquifer in central Wisconsin, we collected a total of four NMR logs and obtained measurements of K in their immediate vicinity with a direct‐push permeameter (DPP). Using a bootstrap algorithm to calibrate the Schlumberger‐Doll Research (SDR) NMR‐K model, we estimated K to within a factor of 5 of the DPP measurements. The lowest levels of accuracy occurred in the lower‐K (K < 10⁻⁴ m/s) intervals. We also evaluated the applicability of prior SDR model calibrations. We found the NMR calibration parameters varied with K, suggesting the SDR model does not incorporate all the properties of the pore space that control K. Thus, the expected range of K in an aquifer may need to be considered during calibration of NMR‐K models. This study is the first step toward establishing NMR logging as an effective method for estimating K in glacial aquifers.

中文翻译：

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核磁共振测井评估冰层含水率的评估。

在美国，冰川含水层是重要的地下水来源，需要准确的特征描述才能做出明智的管理决策。这是理解地下水的运动至关重要的一个参数是水力传导系数，ķ。核磁共振（NMR）测井可测量与地质材料中的水有关的NMR响应。通过利用外部磁场操纵与¹ H相关的核自旋，可以测量核磁化随时间的衰减。这种测井方法可以提供一种有效的方法来估算亚米垂直分辨率下的K，但是将NMR测量与K相关的模型需要校准。在威斯康星州中部一个冰川含水层的两个现场，我们收集了总共四个NMR测井曲线，并使用直接推式渗透仪（DPP）获得了它们附近的K值。使用自举算法校准Schlumberger-Doll Research（SDR）NMR- K模型，我们将K估计为DPP测量值的5倍之内。最低的准确性发生在较低的K（K <  10 ^-4  m / s）间隔内。我们还评估了以前的SDR模型校准的适用性。我们发现NMR校准参数随K变化，表明SDR模型并未纳入控制K的孔隙空间的所有属性。因此，在校准NMR- K模型时，可能需要考虑含水层中K的预期范围。这项研究是建立NMR测井作为估算冰层含水量K的有效方法的第一步。