TR32-Database: Database of Transregio 32

[1067] - Understanding NMR relaxometry of partially water-saturated rocks

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Mohnke, O., Nordlund, C., Jorand, R., Klitzsch, N., 2014. Understanding NMR relaxometry of partially water-saturated rocks. Hydrology and Earth System Sciences, (submitted manuscript), 1 - 15.
Title(s):Main Title: Understanding NMR relaxometry of partially water-saturated rocks
Description(s):Abstract: Nuclear Magnetic Resonance (NMR) relaxometry measurements are commonly used to characterize the storage and transport properties of water-saturated rocks. These assessments are based on the proportionality of NMR signal amplitude and relaxation time to porosity (water content) and pore size, respectively. The relationship between pore size and NMR relaxation time depends on pore shape, which is usually assumed to be spherical or cylindrical. However, the NMR response at partial water saturation for natural sediments and rocks differs strongly from the response calculated for spherical or cylindrical pores, because these pore shapes cannot account for water menisci remaining in the corners of de-saturated angular pores. Therefore, we consider a bundle of pores with triangular cross-sections. We introduce analytical solutions of the NMR equations at partial saturation of these pores, which account for water menisci of de-saturated pores. After developing equations that describe the water distribution inside the pores, we calculate the NMR response at partial saturation for imbibition and drainage based on the deduced water distributions. For this pore model, NMR amplitude and NMR relaxation time at partial water saturation strongly depend on pore shape even so the NMR relaxation time at full saturation only depends on the surface to volume ratio of the pore. The pore-shape-dependence at partial saturation arises from the pore shape and capillary pressure dependent water distribution in pores with triangular cross-sections. Moreover, we show the qualitative agreement of the saturation dependent relaxation time distributions of our model with those observed for rocks and soils.
Responsible Party
Creator(s):Author: Oliver Mohnke
Author: Christopher Nordlund
Author: Rachel Jorand
Author: Norbert Klitzsch
TR32 Topic:Soil
Subject(s):CRC/TR32 Keywords: NMR
File Details
File Name:Mohnke_HESS_2014_submitted.pdf
Data Type:Text
File Size:1056 kB (1.031 MB)
Date(s):Date Submitted: 2014-09-15
Mime Type:application/pdf
Data Format:PDF
Status:In Process
Download Permission:OnlyTR32
General Access and Use Conditions:According to the TR32DB data policy agreement.
Access Limitations:According to the TR32DB data policy agreement.
Licence:TR32DB Data policy agreement
North:-no map data
Measurement Region:Laboratory
Measurement Location:--Laboratory--
Specific Informations - Publication
Article Type:Journal
Source:Hydrology and Earth System Sciences
Volume:(submitted manuscript)
Page Range:1 - 15
Metadata Details
Metadata Creator:Tanja Kramm
Metadata Created:2014-09-18
Metadata Last Updated:2014-09-18
Funding Phase:2
Metadata Language:English
Metadata Version:V40
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