Dynamic correlations between inhomogeneous magnetic fields, internal gradients, diffusion and transverse relaxation, as a probe for pore geometry and heterogeneity

In this study we have applied 2D NMR experiments where the spatial inhomogeneous magnetic field (Bi) inside a porous sample is correlated to respectively internal gradient (G0), diffusion coefficient (D), and transverse relaxation time (T2) of a confined liquid. Experiments were performed on samples having different pore system geometry and heterogeneity, leading to different types of confinement of the liquid. The results show that the correlation between G0 and Bi is more sensitive to the type of confinement, and thus also of the pore geometry and heterogeneity, compared to the corresponding correlations involving D and T2

Dynamic correlations between susceptibility gradients and T 2 -relaxation as a probe for wettability properties of liquid saturated rock cores

We explore the use of correlations between susceptibility gradients, G0, and T2-relaxation (G0-T2), and show how the difference in response for oil and water with respect to G0 can be used for improved characterization of wettability of the internal surface in porous rock cores

Investigating effects from restricted diffusion in multi-component diffusion data

We have investigated model systems in which effects from non-Gaussian restricted diffusion could be separated from effects caused by multiple diffusion coefficients. We applied various models to analyze the experimental data. An analysis based on multi-exponential models does not account correctly for effects caused by restricted diffusion in a system with multiple compartments. However, separating the components due to differences in dynamic behavior prior to the diffusion analysis, combined with a diffusion analysis based on the second cumulant approximation, was more robust, and was able to handle effects from restricted diffusion in the presence of multi-component diffusion

High frequency modulated gradient spin echo diffusion measurements with chemical shift resolution

We present a Modulated Gradient Spin Echo pulse sequence that enables diffusion measurements with chemical shift resolution in the obtained spectra at higher modulation frequencies (1600 Hz) than previously obtained. The modulation is generated using a Carr- Purcell-Meiboom-Gill train of radiofrequency pulses in a constant gradient. To avoid distortions from eddy currents, a longitudinal eddy current delay was added between gradient modulation and spectrum acquisition. To suppress the effects from gradient-slicing and unwanted coherences, while maintaining high chemical shift resolution, short samples (height of 0.5 mm) were prepared in a 5 mm Shigemi™ tube. The pulse sequence was successfully tested on a sample of distilled water and a sample of a water-continuous microemulsion (Winsor’s type I)

Investigating pore to pore exchange in systems saturated with water and oil

Relaxation Exchange Spectroscopy (REXSY) has not previously been performed on samples containing different liquids. We present a pulse sequence that combines a Pulsed Gradient Spin Echo with REXSY, which we call PGSE-REXSY. Using this pulse sequence it is possible to separate the signals from two liquid components, here oil and water, simultaneously present within a sample due to the difference in diffusion properties. A REXSY analysis can then be performed on the individual liquids. The technique is very relevant to applications in petroleum research, and could potentially be used to determine how the mobility of one liquid is influenced by the presence of the other. We also show that compared to a two-dimensional Inverse Laplace Transform, a discrete multi-exponential component model is more robust when performing a quantitative analysis of REXSY data

31P solid-state NMR on skeletal muscle of wild and farmed Atlantic salmon

publishedVersio

High frequency modulated gradient spin echo diffusion measurements with chemical shift resolution

We present a Modulated Gradient Spin Echo pulse sequence that enables diffusion measurements with chemical shift resolution in the obtained spectra at higher modulation frequencies (1600 Hz) than previously obtained. The modulation is generated using a Carr- Purcell-Meiboom-Gill train of radiofrequency pulses in a constant gradient. To avoid distortions from eddy currents, a longitudinal eddy current delay was added between gradient modulation and spectrum acquisition. To suppress the effects from gradient-slicing and unwanted coherences, while maintaining high chemical shift resolution, short samples (height of 0.5 mm) were prepared in a 5 mm Shigemi™ tube. The pulse sequence was successfully tested on a sample of distilled water and a sample of a water-continuous microemulsion (Winsor’s type I)

Dynamic correlations between inhomogeneous magnetic fields, internal gradients, diffusion and transverse relaxation, as a probe for pore geometry and heterogeneity

In this study we have applied 2D NMR experiments where the spatial inhomogeneous magnetic field (Bi) inside a porous sample is correlated to respectively internal gradient (G0), diffusion coefficient (D), and transverse relaxation time (T2) of a confined liquid. Experiments were performed on samples having different pore system geometry and heterogeneity, leading to different types of confinement of the liquid. The results show that the correlation between G0 and Bi is more sensitive to the type of confinement, and thus also of the pore geometry and heterogeneity, compared to the corresponding correlations involving D and T2

Dynamic correlations between inhomogeneous magnetic fields, internal gradients, diffusion and transverse relaxation, as a probe for pore geometry and heterogeneity

In this study we have applied 2D NMR experiments where the spatial inhomogeneous magnetic field (Bi) inside a porous sample is correlated to respectively internal gradient (G0), diffusion coefficient (D), and transverse relaxation time (T2) of a confined liquid. Experiments were performed on samples having different pore system geometry and heterogeneity, leading to different types of confinement of the liquid. The results show that the correlation between G0 and Bi is more sensitive to the type of confinement, and thus also of the pore geometry and heterogeneity, compared to the corresponding correlations involving D and T2