Enhanced Transverse Relaxation in Porous Media due to Internal Field Gradients

2002 ◽  
Vol 156 (2) ◽  
pp. 171-180 ◽  
Author(s):  
Keh-Jim Dunn
Keyword(s):  
Porous Media ◽  
Internal Field ◽  
Transverse Relaxation ◽  
Field Gradients ◽  
Internal Field Gradients

Interpretation of restricted diffusion in sandstones with internal field gradients

2001 ◽  
Vol 19 (3-4) ◽  
pp. 535-537 ◽  
Author(s):  
Matthias Appel ◽  
J.Justin Freeman ◽  
John S. Gardner ◽  
George H. Hirasaki ◽  
Q.Gigi Zhang ◽  
...  
Keyword(s):  
Internal Field ◽  
Restricted Diffusion ◽  
Field Gradients ◽  
Internal Field Gradients

scholarly journals Combination of MRI and SEM to Assess Changes in the Chemical Properties and Permeability of Porous Media due to Barite Precipitation

Minerals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 226 ◽  
Author(s):  
Jenna Poonoosamy ◽  
Sabina Haber-Pohlmeier ◽  
Hang Deng ◽  
Guido Deissmann ◽  
Martina Klinkenberg ◽  
...  
Keyword(s):  
Porous Media ◽  
Magnetic Resonance ◽  
Reactive Transport ◽  
Relaxation Times ◽  
Chemical Properties ◽  
Column Experiment ◽  
Transverse Relaxation Time ◽  
Gas Production ◽  
Transport Modelling ◽  
Transverse Relaxation

The understanding of the dissolution and precipitation of minerals and its impact on the transport of fluids in porous media is essential for various subsurface applications, including shale gas production using hydraulic fracturing (“fracking”), CO2 sequestration, or geothermal energy extraction. In this work, we conducted a flow through column experiment to investigate the effect of barite precipitation following the dissolution of celestine and consequential permeability changes. These processes were assessed by a combination of 3D non-invasive magnetic resonance imaging, scanning electron microscopy, and conventional permeability measurements. The formation of barite overgrowths on the surface of celestine manifested in a reduced transverse relaxation time due to its higher magnetic susceptibility compared to the original celestine. Two empirical nuclear magnetic resonance (NMR) porosity–permeability relations could successfully predict the observed changes in permeability by the change in the transverse relaxation times and porosity. Based on the observation that the advancement of the reaction front follows the square root of time, and micro-continuum reactive transport modelling of the solid/fluid interface, it can be inferred that the mineral overgrowth is porous and allows the diffusion of solutes, thus affecting the mineral reactivity in the system. Our current investigation indicates that the porosity of the newly formed precipitate and consequently its diffusion properties depend on the supersaturation in solution that prevails during precipitation.

scholarly journals Spin-Noise Gradient Echoes

2021 ◽  
Author(s):  
Victor V. Rodin ◽  
Stephan J. Ginthör ◽  
Matthias Bechmann ◽  
Hervé Desvaux ◽  
Norbert Müller
Keyword(s):  
Field Gradient ◽  
Magnetic Field Gradient ◽  
Relaxation Times ◽  
Difference Spectra ◽  
Transverse Relaxation ◽  
Transient Phenomena ◽  
Pulsed Field ◽  
Spin Noise ◽  
Field Gradients ◽  
Noise Spectroscopy

Abstract. Nuclear spin-noise spectroscopy in absence of radio frequency pulses was studied under the influence of pulsed field gradients (PFGs) on pure and mixed liquids. Under conditions, where the radiation-damping induced line broadening is smaller than the gradient dependent inhomogeneous broadening, echo responses can be observed in difference spectra between experiments employing pulsed field gradient pairs of same and opposite signs. These observed “spin-noise gradient echoes” (SNGEs) were analyzed through a simple model to describe the effects of transient phenomena. Experiments performed on high resolution NMR probes demonstrate how “refocused spin noise” behaves and how it can be exploited to determine sample properties. In bulk liquids and their mixtures transverse relaxation times as well as translational diffusion constants can be determined from SNGE spectra recorded following tailored sequences of magnetic field gradient pulses.

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