A NMR technique for the analysis of pore structure: Numerical inversion of relaxation measurements

Munn, Kevin; Smith, Douglas M.

doi:10.1016/0021-9797(87)90250-5

Cited by 90 publications

(28 citation statements)

References 14 publications

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“…This is an inherently ill-posed problem and requires some constraints to produce a stable solution. Here we use Tikhonov regularisation [52,53] with the smoothing parameter determined by the Generalized Cross Validation (GCV) method [54,55]. In addition, scanning electron microscopy (SEM) images were acquired to analyse the pore structure.…”

Section: Methodsmentioning

confidence: 99%

Magnetic resonance imaging studies of spontaneous capillary water imbibition in aerated gypsum

Song¹,

Mitchell²,

Jaffel³

et al. 2011

J. Phys. D: Appl. Phys.

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In this paper we investigate both capillary water imbibition and the sorptivity of aerated gypsum plaster, and how these sorption characteristics are related to the pore structure of the material. These characteristics are examined by monitoring mass change using the conventional gravimetric method and by obtaining water content profiles using non-destructive magnetic resonance imaging (MRI) techniques during capillary imbibition of water. Here, three different gypsum samples are investigated: one non-aerated reference gypsum sample and two aerated gypsum samples produced with different volumetric air fractions. The capillary water absorption into the reference sample follows t 1/2 kinetics (Fickian diffusion), where t is the time of ingress. However, in the aerated gypsum samples there are deviations from t 1/2 kinetics. The MRI results show unambiguously that two wetting fronts advance through the aerated structure; an observation that cannot be made from the gravimetric data alone. The water content profiles of the aerated gypsum samples are therefore analysed by treating them as the sum of two separate absorption processes using sharp front analysis. The capillary water absorption properties of this material are well described as a parallel combination of fast absorption into fine matrix pores and slow absorption into a modified structure of matrix pores inter-connected to air voids introduced into the slurry by aeration.

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Section: Methodsmentioning

confidence: 99%

Magnetic resonance imaging studies of spontaneous capillary water imbibition in aerated gypsum

Song¹,

Mitchell²,

Jaffel³

et al. 2011

J. Phys. D: Appl. Phys.

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“…The solution, then, depends critically on the relative weighting of the regularizing term. Several different methods have been reported (Munn and Smith 1987;Kroeker and Henkelman 1986;Whittall and MacKay 1989;Borgia et al 1998). A nonnegative least-squares minimization method is often used to ensure non-negative coefficients are obtained (Munn and Smith 1987).…”

Section: Continuous Formulationmentioning

confidence: 99%

“…A number of groups have advanced the use of a continuous distribution function for representing relaxation (Kroeker and Henkelman 1986;Munn and Smith 1987;Whittall and MacKay 1989;Borgia et al 1998). However, they have all used parametric regression methods to estimate values for the distribution function at a set of specified relaxation times, rather than seeking to estimate the entire distribution function.…”

Section: Continuous Formulationmentioning

confidence: 99%

A Nonparametric Approach for Determining NMR Relaxation Distributions

Watson

2014

Transp Porous Med

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Nuclear magnetic resonance (NMR) and imaging (MRI) can provide unique information about fluid distributions, flow, transport properties, and morphology within permeable media. The mathematical description of NMR relaxation of fluids in permeable media is one key element used to develop such information. We introduce and evaluate nonparametric regression theory to determine continuous relaxation distribution functions from NMR/MRI experiments. Unlike other methods, ours is based on determining the best estimate of the distribution function from experimental data. Our method is robust and does not require user interventions, so it is particularly valuable for accurately determining fluid distributions from MRI experiments. Such information is essential for determining porosity, permeability, and fluid saturation distributions, as well as permeable media morphologies.

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“…The principles of NMR relaxation are explained below. Therefore several workers (18)(19)(20) have used this method to derive pore size distributions independent of the pore shielding effects found in mercury porosimetry and nitrogen desorption. In combination with imaging methods, NMR relaxometry has recently (21) been used to provide a spatially resolved pore size distribution.…”

Section: Introductionmentioning

confidence: 99%

Characterization of Macroscopic Structural Disorder in Porous Media Using Mercury Porosimetry

Rigby¹,

Fletcher²,

Riley³

2001

Journal of Colloid and Interface Science

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A NMR technique for the analysis of pore structure: Numerical inversion of relaxation measurements

Cited by 90 publications

References 14 publications

Magnetic resonance imaging studies of spontaneous capillary water imbibition in aerated gypsum

Magnetic resonance imaging studies of spontaneous capillary water imbibition in aerated gypsum

A Nonparametric Approach for Determining NMR Relaxation Distributions

Characterization of Macroscopic Structural Disorder in Porous Media Using Mercury Porosimetry

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