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An Extended Model for Predicting Hydraulic Conductivity from NMR Measurements
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, Near Surface 2011 - 17th EAGE European Meeting of Environmental and Engineering Geophysics, Sep 2011, cp-253-00073
- ISBN: 978-90-73834-15-6
Abstract
The prediction of hydraulic conductivity (K) from NMR measurements (Phi, T2) can be applied successfully on sandstones. For hydrological applications in the near surface unconsolidated material is more common. This material generally shows less variability in porosities but a larger range of pore sizes compared to sandstones. The known (semi-)empiric K-T2 relations have often be extended to this field of application but their validity needs to be verified. In this work we present a simple model based on tube pores, which is valid for the whole range of laminar flow from silt to gravel. By considering the slow diffusion regime we are able to estimate a maximum K from a measured T2 time. The model replaces the empiric factors in known K-T2 relations with (petro-)physical parameters. This enables to separate effects caused by variations of the surface relaxivity, a material characteristic that links T2 to the inner surface of the material, from variations of other parameters. This may help to reduce the range of the predicted K-values from NMR measurement on similar materials and enable to incorporate results from ofter methods.