Differentiating Diffusivity in Different Channels of ZSM‐5 Zeolite by Pulsed Field Gradient (PFG) NMR

ChemCatChem ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 463-468
Author(s):  
Shu Zeng ◽  
Shutao Xu ◽  
Shushu Gao ◽  
Mingbin Gao ◽  
Wenna Zhang ◽  
...  
Keyword(s):  
Field Gradient ◽  
Pulsed Field ◽  
Pfg Nmr

New Technique for Evaluating Fracture Geometry and Preferential Orientation Using Pulsed Field Gradient Nuclear Magnetic Resonance

SPE Journal ◽  
2021 ◽  
pp. 1-14
Author(s):  
Mahmoud Elsayed ◽  
Ammar El-Husseiny ◽  
Hyung Kwak ◽  
Syed Rizwanullah Hussaini ◽  
Mohamed Mahmoud
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Diffusion Coefficient ◽  
Fluid Flow ◽  
Magnetic Resonance ◽  
Field Gradient ◽  
Preferential Orientation ◽  
Pore Geometry ◽  
Pulsed Field ◽  
Pfg Nmr

Summary In-situ evaluation of fracture tortuosity (i.e., pore geometry complexity and roughness) and preferential orientation is crucial for fluid flow simulation and production forecast in subsurface water and hydrocarbon reservoirs. This is particularly significant for naturally fractured reservoirs or postacid fracturing because of the strong permeability anisotropy. However, such downhole in-situ characterization remains a challenge. This study presents a new method for evaluating fracture tortuosity and preferential orientation based on the pulsed field gradient (PFG) nuclear magnetic resonance (NMR) technique. Such an approach provides diffusion tortuosity, τd, defined as the ratio of bulk fluid diffusion coefficient to the restricted diffusion coefficient in the porous media. In the PFG NMR technique, the magnetic field gradient can be applied in different directions, and therefore anisotropy in diffusion coefficient and τd can be evaluated. Three 3D printed samples, characterized by well controlled variable fracture tortuosity, one fractured sandstone, and three acidized carbonate samples with wormhole were used in this study. PFG NMR measurements were performed using both 2- and 12-MHz NMR instruments to obtain τd in the three different principal directions. The results obtained from the NMR measurements were compared with fracture tortuosity and preferential orientation determined from the microcomputed tomography (micro-CT) images of the samples. The results showed that τd increases as the fracture tortuosity and pore geometry complexity increases, showing good agreement with the image-based geometric tortuosity values. Moreover, the lowest τd values were found to coincide with the preferential direction of fracture surfaces and wormhole body for a given sample, whereas the maximum τd values correspond to the nonconnected pathway directions. These results suggest that the implantation of directional restricted diffusion measurements on the NMR well logging tools would offer a possibility of probing tortuosity and determining preferential fluid flow direction via direct downhole measurements.

scholarly journals Three-dimensional pulsed field gradient NMR measurements of self-diffusion in anisotropic materials for energy storage applications

2019 ◽  
Vol 21 (8) ◽  
pp. 4538-4546 ◽  
Author(s):  
S. Engelke ◽  
L. E. Marbella ◽  
N. M. Trease ◽  
M. De Volder ◽  
C. P. Grey
Keyword(s):  
Energy Storage ◽  
Porous Silicon ◽  
Field Gradient ◽  
Three Dimensional ◽  
Pulsed Field ◽  
Self Diffusion ◽  
Silicon Structures ◽  
Energy Storage Applications ◽  
Nmr Methods ◽  
Pfg Nmr

The ability to resolve solvent in- and outside of the pores of mesoscopic porous silicon structures allows the effect of confinement on transport to be explored by 1H and 7Li PFG NMR methods and pore diameters and lengths to be estimated.

Assessing Guest-Molecule Diffusion in Heterogeneous Powder Samples of Metal-Organic Frameworks through Pulsed-Field-Gradient (PFG) NMR Spectroscopy

2017 ◽  
Vol 23 (53) ◽  
pp. 13000-13005 ◽  
Author(s):  
Roland Thoma ◽  
Jörg Kärger ◽  
Nader de Sousa Amadeu ◽  
Sandra Nießing ◽  
Christoph Janiak
Keyword(s):  
Nmr Spectroscopy ◽  
Field Gradient ◽  
Guest Molecule ◽  
Metal Organic Frameworks ◽  
Pulsed Field ◽  
Powder Samples ◽  
Metal Organic ◽  
Pfg Nmr

scholarly journals Ethane diffusion in mixed linker zeolitic imidazolate framework-7-8 by pulsed field gradient NMR in combination with single crystal IR microscopy

2018 ◽  
Vol 20 (37) ◽  
pp. 23967-23975 ◽  
Author(s):  
Samuel Berens ◽  
Christian Chmelik ◽  
Febrian Hillman ◽  
Jörg Kärger ◽  
Hae-Kwon Jeong ◽  
...  
Keyword(s):  
Single Crystal ◽  
Field Gradient ◽  
Experimental Conditions ◽  
Zeolitic Imidazolate Framework ◽  
Pulsed Field Gradient Nmr ◽  
Pulsed Field ◽  
Ir Microscopy ◽  
Pfg Nmr

Pulsed field gradient (PFG) NMR was used in combination with single crystal IR microscopy (IRM) to study diffusion of ethane inside crystals of a mixed linker zeolitic imidazolate framework (ZIF) of the type ZIF-7-8 under comparable experimental conditions.

The Measurement of Tortuosity of Porous Media Using Imaging, Electrical Measurements, and Pulsed Field Gradient NMR

2021 ◽  
Author(s):  
Mahmoud Elsayed ◽  
Hyung Kwak ◽  
Ammar El-Husseiny ◽  
Mohamed Mahmoud
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Porous Media ◽  
Diffusion Coefficient ◽  
Magnetic Resonance ◽  
Field Gradient ◽  
Pulsed Field ◽  
Self Diffusion ◽  
Pfg Nmr ◽  
The Relationship ◽  
Self Diffusion Coefficient

Abstract Tortuosity, in general characterizes the geometric complexity of porous media. It is considered as one of the key factors in characterizing the heterogonous structure of porous media and has significant implications for macroscopic transport flow properties. There are four widely used definitions of tortuosity, that are relevant to different fields from hydrology to chemical and petroleum engineering, which are: geometric, hydraulic, electrical, and diffusional. Recent work showed that hydraulic, electrical and diffusional tortuosity values are roughly equal to each other in glass beads. Nevertheless, the relationship between the different definitions of Tortuosity in natural rocks is not well understood yet. Understanding the relationship between the different Tortuosity definitions in rocks can help to establish a workflow that allows us to estimate other types from the available technique. Therefore, the objective of this study is to investigate the relationship between the different tortuosity definitions in natural rocks. A major focus of this work is to utilize Nuclear Magnetic Resonance (NMR) technology to estimate Tortuosity. Such technique has been traditionally used to obtain diffusional tortuosity which can be defined as the ratio of the free fluid self-diffusion coefficient to the restricted fluid self-diffusion coefficient inside the porous media. In this study, the following techniques were used to quantify hydraulic, electrical, and diffusional tortuosity respectively on the same rock sample: (1) Microcomputed Tomography 3D imaging (2) Four-Electrodes resistivity measurements (3) Pulsed-Field Gradient Nuclear Magnetic Resonance (PFG NMR). PFG NMR is very powerful, non-invasive technique employed to measure the self-diffusion coefficient for free and confined fluids. The measurements were done based on two carbonate rock core plugs characterized by variable porosity, permeability and texture complexity. Results show that PFG NMR can be applied directionally to quantify the pore network anisotropy created by fractures. For both samples, hydraulic tortuosity was found to have the lowest magnitude compared to geometric, electrical and diffusional tortuosity. This could be explained by the more heterogeneous microstructure of carbonate rocks. NMR technique has however advantages over the other electrical and imaging techniques for tortuosity characterization: it is faster, non-destructive and can be applied in well bore environment (in situ). We therefore conclude that NMR can provide a tool for estimating not only diffusional tortuosity but also for indirectly obtaining hydraulic and electrical tortuosity.

Robustness of Methane Diffusion in Geometrically Restricted Molecular Sieve Pores

1994 ◽  
Vol 366 ◽  
Author(s):  
Sriram S. Nivarthi ◽  
H. Ted Davis ◽  
Alon V. McCormick
Keyword(s):  
Field Gradient ◽  
Molecular Sieve ◽  
Pore Space ◽  
Pulsed Field Gradient Nmr ◽  
Pulsed Field ◽  
Zeolite Nay ◽  
Self Diffusion ◽  
Methane Diffusion ◽  
Pfg Nmr ◽  
Sieve Pores

ABSTRACTNMR measurements of sorbate mobility in zeolites are especially attractive because of their capability of measuring multicomponent and anisotropic self-diffusion. We have recently reported the application of the pulsed field gradient NMR technique using very large zeolite crystals to study how easily methane can diffuse when we attempt to slow its migration by crowding the pore space. Here we analyze the implications of these PFG NMR experiments involving (i) ethylene blocking of methane in zeolite NaY; and (ii) methane molecules trying to pass one another in the molecular sieve A1PO4-5.

The gel-forming behaviour of dextran in the presence of KCl: a quantitative 13C and pulsed field gradient (PFG) NMR study

2003 ◽  
Vol 104 (1) ◽  
pp. 131-140 ◽  
Author(s):  
L Naji ◽  
J Schiller ◽  
J Kaufmann ◽  
F Stallmach ◽  
J Kärger ◽  
...  
Keyword(s):  
Field Gradient ◽  
Pulsed Field ◽  
Nmr Study ◽  
Pfg Nmr ◽  
Forming Behaviour
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