Characterization of Structure and Transport in Porous Media by Pulsed Field Gradient (PFG) NMR Technique. Part I: Master Curve and Characteristic Inner Length

2006 ◽  
Vol 29 (7) ◽  
pp. 847-853 ◽  
Author(s):  
M. Bardakci ◽  
J. E. Tillich ◽  
M. Holz
Keyword(s):  
Porous Media ◽  
Field Gradient ◽  
Master Curve ◽  
Pulsed Field ◽  
Transport In Porous Media ◽  
Pfg Nmr

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.

NMR relaxation and pulsed field gradient study of alginate bead porous media

2004 ◽  
Vol 169 (2) ◽  
pp. 203-214 ◽  
Author(s):  
Melanie M Britton ◽  
Robin G Graham ◽  
Ken J Packer
Keyword(s):  
Porous Media ◽  
Field Gradient ◽  
Alginate Bead ◽  
Nmr Relaxation ◽  
Pulsed Field

scholarly journals Nuclear Magnetic Resonance (NMR) Characterization of a Polymerized Ionic Liquid Electrolyte Material

2012 ◽  
Vol 1440 ◽  
Author(s):  
A.L. Michan ◽  
G.T.M. Nguyen ◽  
O. Fichet ◽  
F. Vidal ◽  
C. Vancaeyzeele ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Field Gradient ◽  
Diffusion Coefficients ◽  
Polymer Network ◽  
Relaxation Times ◽  
Solid Polymer ◽  
Pulsed Field ◽  
Nuclear Magnetic

ABSTRACTSolid electrolyte materials have the potential to improve performance and safety characteristics of lithium-ion batteries by replacing conventional solvent-based electrolytes. A candidate solid polymer electrolyte, AMLi/PEGDM, has been synthesized by crosslinking an anionic monomer AMLi, with poly(ethylene glycol) dimethacrylate. The main goal of the synthesis is to produce a single-ion conducting polymer network where lithium cations can move freely and fluorinated anions are immobilized as part of the polymer network. A comprehensive characterization of anion and cation mobility in the resulting material is therefore required. Using pulsed-field gradient nuclear magnetic resonance (PFG-NMR), we are able to measure and quantify the individual diffusion coefficients of mobile species in the material (19F and 7Li) and confirm the extent to which the fluorinated anionic component is immobilized. We have characterized dry (σ~3.0 x10-7 S/cm at 30°C) and propylene carbonate (PC) saturated gel (σ~1.0x10-4 S/cm at 30°C) samples. Experimental results include NMR spin-spin and spin-lattice relaxation times in addition to diffusion coefficient measurements over a temperature range up to 100°C. Practically, the diffusion measurements are extremely challenging, as the spin-spin (T2) relaxation times are very short, necessitating the development of specialized pulsed-field gradient apparatus. Diffusion coefficients for the most mobile components of the lithium cations and fluorinated anions at 100°C in dry membranes have been found to be 3.4 x10-8 cm2/s and 2.1 x10-8 cm2/s respectively. These results provide valuable insight into the conduction mechanisms in these materials, and will drive further optimization of solid polymer electrolytes.

Fractal characterization of dynamic structure of foam transport in porous media

2017 ◽  
Vol 241 ◽  
pp. 675-683 ◽  
Author(s):  
Fei Wang ◽  
Zhaomin Li ◽  
Hailong Chen ◽  
Qichao Lv ◽  
Wanambwa Silagi ◽  
...  
Keyword(s):  
Porous Media ◽  
Dynamic Structure ◽  
Transport In Porous Media

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.

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