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‣ NMR imaging of fluid pathways during drainage of softwood in a pressure membrane chamber

ALMEIDA, G.; LECLERC, S.; PERRE, P.
Fonte: PERGAMON-ELSEVIER SCIENCE LTD Publicador: PERGAMON-ELSEVIER SCIENCE LTD
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
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An experiment was implemented to study fluid flow in a pressure media. This procedure successfully combines nuclear magnetic resonance imaging with a pressure membrane chamber in order to visualize the non-wetting and wetting fluid flows with controlled boundary conditions. A specially designed pressure membrane chamber, made of non-magnetic materials and able to withstand 4 MPa, was designed and built for this purpose. These two techniques were applied to the drainage of Douglas fir sapwood. In the study of the longitudinal flow, narrow drainage fingers are formed in the latewood zones. They follow the longitudinal direction of wood and spread throughout the sample length. These fingers then enlarge in the cross-section plane and coalesce until drainage reaches the whole latewood part. At the end of the experiments, when the drainage of liquid water in latewood is completed, just a few sites of percolation appear in earlywood zones. This difference is a result of the wood anatomical structure, where pits, the apertures that allow the sap to flow between wood cells, are more easily aspirated in earlywood than in latewood. (C) 2007 Elsevier Ltd. All rights reserved.

‣ Desenvolvimento de metodologias para o estudo de meios porosos por ressonância magnética nuclear; Development of methodologies for the study of porous media by nuclear magnetic resonance

d'Eurydice, Marcel Nogueira
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 02/06/2011 Português
Relevância na Pesquisa
59.32642%
O presente trabalho teve como objetivo a implementação de técnicas de Ressonância Magnética Nuclear (RMN) para o estudo de meios porosos em geral, com potenciais aplicações no estudo de rochas, ossos, polímeros e materiais cerâmicos porosos. Devido à heterogeneidade e à complexidade desses meios, torna-se importante correlacionar variados parâmetros físicos que contenham informações tanto sobre a dinâmica molecular quanto sobre a estrutura físico-química dos poros e dos fluidos que os permeiam. Utilizando técnicas de RMN, é possível investigar esses parâmetros através da medida dos coeficientes de difusão e dos tempos de relaxação longitudinal e transversal dos fluidos presentes nos poros, que apresentam diferentes estados dinâmicos, variando desde um líquido isotrópico até um líquido com alta viscosidade ou organizado devido à sua interação com a superfície dos poros ou com partículas presentes nos fluidos. Para isso, foram empregadas técnicas de RMN baseadas especialmente em medidas de tempos de relaxação transversal que, quando adequadamente combinadas, permitem a construção de mapas bidimensionais que correlacionam propriedades da dinâmica molecular de fluidos saturantes nessas amostras em instantes diferentes do experimento...

‣ Programação de um sistema de controle de RF e aquisição de dados para um espectrômetro de RMN de baixo custo; Programming of a RF control sistem and data acquisition for a lowcost NMR spectrômeter

Andreeta, Mariane Barsi
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 16/02/2012 Português
Relevância na Pesquisa
58.95063%
Este projeto teve como objetivo a construção e automatização de um espectrômetro de baixo custo que tem como principal aplicação a caracterização de meios porosos. Para realizar a caracterização de um meio poroso é necessário que o campo magnético externo aplicado não seja intenso para diminuir os problemas relacionados com a diferença de susceptibilidade magnética na interface fluido-solido. Por este motivo, foi construído um magneto resistivo de baixo campo, operando na frequência de próton de 2MHz (0.047 Tesla) e de simples design. Para manter o equipamento com custo mais baixo possível foram construídos em laboratório a fonte de alimentação do magneto, um amplificador ajustado para 2MHz e os componentes λ/4 e os softwares necessários. O software desenvolvido tem a finalidade de controlar a placa de geração e aquisição de radiofrequência que foi adquirida pela empresa Spincore, denominada RadioProcessor. Para esta finalidade optou-se pela construção de uma nova API na linguagem C++, utilizando a API original do RadioProcessor como base, de forma a montar um conjunto de funções simples e intuitivas para a utilização do espectrômetro. Além disso, foi realizada a integração de uma linguagem script à biblioteca...

‣ Estudo de cerâmicas porosas de alumina através da medida de tempos de relaxação via ressonância magnética nuclear; Characterization of porous alumina ceramics through measurement of nuclear magnetic resonance relaxation times

Montrazi, Elton Tadeu
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 29/03/2012 Português
Relevância na Pesquisa
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A medida de tempo de relaxação longitudinal (T1) e transversal (T2) de ressonância magnética nuclear (RMN) é muito utilizada para análise de meios porosos na área do petróleo. Esses tempos de relaxação estão relacionados com tamanho dos poros. As cerâmicas, dependendo da sua temperatura de sinterização, apresentam uma porosidade intrínseca, mas cerâmicas especiais para processo de filtragem e escafoldes de implantes ósseos necessitam de poros maiores e de permeabilidade para suas aplicações. Esse objetivo é alcançado introduzindo um agente porogênico, um material degradável com a temperatura, obtendo assim poros induzidos além dos intrínsecos. O agente porogênico escolhido para este trabalho foi cristais de sacarose, os tamanhos dos poros são controláveis pelo tamanho dos cristais e pela quantidade, tornado esse um meio factível nos estudos de RMN através dos tempos de relaxação. Foram selecionadas, através de peneiras, duas faixas de tamanhos de cristais de sacarose: G (grande) com limite superior de 600μm e inferior de 300μm e P (pequeno) com tamanhos na faixa de 38μm a 150μm. A cerâmica preparada com P apresentou distribuição de tamanho de poros (de 15 à 105μm) com mediana em 40μm...

‣ Utilização da RMN no estudo de rochas reservatório siliciclásticas; Utilization of NMR in the study of siliciclastic reservoir rocks

Silva, Rodrigo de Oliveira
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 17/10/2014 Português
Relevância na Pesquisa
58.332334%
Este trabalho foi desenvolvido utilizando-se rochas reservatório siliciclásticas provenientes de afloramentos brasileiros, pertencentes ao Grupo Guaritas (Caçapava do Sul e Pinheiro Machado - RS) e à Formação Pirambóia (Rio Claro - SP), com o objetivo de se obter suas características petrofísicas. As amostras são provenientes de diferentes fácies eólicas e pluviais, com características semelhantes a reservatórios de água e hidrocarbonetos. Foram utilizados experimentos de Ressonância Magnética Nuclear (RMN), intrusão de mercúrio, susceptibilidade magnética, análise de lâmina petrográfica e Espectroscopia de Fluorescência de Energia Dispersiva de Raios-X (EDX) para a análise das amostras. Apesar de serem provenientes de sistemas deposicionais similares, a correlação entre os resultados demonstrou que a diagênese tem importante papel no desenvolvimento dos reservatórios, influenciando na porosidade e permeabilidade das amostras. Foi demonstrado que a susceptibilidade magnética possui correlação com as quantidades de Fe 203, Al 203 e SiO2, onde o Al 203 está relacionado com a quantidade de argila das amostras (aluminossilicatos). Através dos resultados de RMN foi possível estimar a susceptibilidade magnética das amostras através da largura de linha espectral em baixo campo. As estimativas de porosidade e tamanhos de poros via RMN demonstraram compatibilidade com as análises das lâminas e experimentos de intrusão de mercúrio. Com os experimentos de RMN bidimensionais T1xT2...

‣ Difusão de spins nucleares em meios porosos - uma abordagem computacional da RMN; Nuclear spin diffusion in porous media - a computational approach of NMR

Oliveira, Éverton Lucas de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 19/02/2015 Português
Relevância na Pesquisa
109.51151%
A Ressonância Magnética Nuclear (RMN) é uma importante técnica empregada nas principais áreas de conhecimento, tais como, Física, Química e Medicina. Importantes trabalhos da RMN aplicada ao estudo da dinâmica de moléculas em fluidos presentes em meios porosos permitiram que esta técnica ganhasse também notoriedade na indústria do petróleo. O presente projeto é fundamentado em alguns destes trabalhos seminais, reproduzindo, através de modelos físico-computacionais, os principais efeitos físicos da difusão e a consequente relaxação dos spins dos núcleos atômicos presentes nas moléculas dos fluidos imersos nos meios porosos. Os métodos teóricos utilizados para a interpretação dos parâmetros de relaxação transversal (T2) e longitudinal (T1), levam em consideração as propriedades macroscópicas da dinâmica de um ensemble de spins nucleares. Para a compreensão da difusão e relaxação nuclear em meios porosos, é de fundamental importância o emprego de métodos físico-computacionais que levam em consideração tanto a microestrutura quanto a difusão translacional dos spins nucleares através desses meios. Dentro dos modelos propostos nesta dissertação, foram utilizados conceitos básicos de mecânica estatística e de relaxação nuclear...

‣ Visualization of gas flow and diffusion in porous media

Kaiser, Lana G.; Meersmann, Thomas; Logan, John W.; Pines, Alexander
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
57.869893%
The transport of gases in porous materials is a crucial component of many important processes in science and technology. In the present work, we demonstrate how magnetic resonance microscopy with continuous flow laser-polarized noble gases makes it possible to “light up” and thereby visualize, with unprecedented sensitivity and resolution, the dynamics of gases in samples of silica aerogels and zeolite molecular sieve particles. The “polarization-weighted” images of gas transport in aerogel fragments are correlated to the diffusion coefficient of xenon obtained from NMR pulsed-field gradient experiments. The technique provides a unique means of studying the combined effects of flow and diffusion in systems with macroscopic dimensions and microscopic internal pore structure.

‣ Noninvasive bipolar double-pulsed-field-gradient NMR reveals signatures for pore size and shape in polydisperse, randomly oriented, inhomogeneous porous media

Shemesh, Noam; Özarslan, Evren; Adiri, Tal; Basser, Peter J.; Cohen, Yoram
Fonte: American Institute of Physics Publicador: American Institute of Physics
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
49.119077%
Noninvasive characterization of pore size and shape in opaque porous media is a formidable challenge. NMR diffusion-diffraction patterns were found to be exceptionally useful for obtaining such morphological features, but only when pores are monodisperse and coherently placed. When locally anisotropic pores are randomly oriented, conventional diffusion NMR methods fail. Here, we present a simple, direct, and general approach to obtain both compartment size and shape even in such settings and even when pores are characterized by internal field gradients. Using controlled porous media, we show that the bipolar-double-pulsed-field-gradient (bp-d-PFG) methodology yields diffusion-diffraction patterns from which pore size can be directly obtained. Moreover, we show that pore shape, which cannot be obtained by conventional methods, can be directly inferred from the modulation of the signal in angular bp-d-PFG experiments. This new methodology significantly broadens the types of porous media that can be studied using noninvasive diffusion-diffraction NMR.

‣ Study of gas flow dynamics in porous and granular media with laser-polarized ¹²⁹Xe NMR

Wang, Ruopeng, 1972-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 182 p.; 8717529 bytes; 8725176 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
48.81079%
This thesis presents Nuclear Magnetic Resonance (NMR) studies of gas flow dynamics in porous and granular media by using laser-polarized ¹²⁹Xe . Two different physical processes, the gas transport in porous rock cores and the mass exchanges between different phases in fluidized granular systems, were investigated and new experimental methods were designed to measure several important parameters characterizing the two systems. Methods for measuring the parameters had been either unavailable or significantly limited previously. The research involved modeling the gas flow in porous and granular media by relating the dynamics of spin magnetization to the interesting parameters, as well as correspondingly designing new measurement methods and verifying them on the laboratory test beds. We proposed a simple method to measure two important parameters of reservoir rocks, permeability and effective porosity, by probing the flow front of laser-polarized xenon gas inside the rock cores. The method was thoroughly tested on different categories of rocks with permeability values spanning two orders of magnitude, and the results were in agreement with those from the established techniques.; (cont.) The uniqueness in the work is that the fast method developed is capable of measuring the two parameters simultaneously on the same setup. Bubble-emulsion exchange and emulsion-adsorption exchange in a fluidized bed are two processes crucial to the efficiency of many chemical reactors working in bubbling regime. We used differences in T2 and chemical shift to contrast the three phases in the xenon spectra...

‣ NMR oil well logging: Diffusional coupling and internal gradients in porous media

Anand, Vivek
Fonte: Universidade Rice Publicador: Universidade Rice
Português
Relevância na Pesquisa
68.665024%
The default assumptions used for interpreting Nuclear Magnetic Resonance (NMR) measurements with reservoir rocks fail for many sandstone and carbonate formations. This study provides quantitative understanding of the mechanisms governing NMR relaxation of formation fluids for two important cases in which default assumptions are not valid. The first is diffusional coupling between micro and macropore, the second is susceptibility-induced magnetic field inhomogeneities. Understanding of governing mechanisms can aid in better estimation of formation properties such as pore size distribution and irreducible water saturation. The assumption of direct correspondence between relaxation time and pore size distribution of a rock fails if fluid in different sized pores is coupled by diffusion. Pore scale simulations of relaxation in coupled micro and macropores are done to analyze the effect of governing parameters such as surface relaxivity, pore geometry and fluid diffusivity. A new coupling parameter (alpha) is introduced which quantifies the extent of coupling by comparing the rate of relaxation in a coupled pore to the rate of diffusional transport. Depending on alpha, the pores can communicate through total, intermediate or decoupled regimes of coupling. This work also develops a new technique for accurate estimation of irreducible saturation...

‣ Recent Fourier and Laplace perspectives for multidimensional NMR in porous media

Callaghan, Paul T; Arns, Christoph; Galvosas, Petrik; Hunter, Mark W; Qiao, Ying; Washburn, Kate
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
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Multidimensional NMR techniques used in the measurement of molecular displacements, whether by diffusion or advection, and in the measurement of nuclear spin relaxation times are categorised. Fourier-Fourier, Fourier-Laplace and Laplace-Laplace methods ar

‣ Multidimensional NMR inverse Laplace Spectroscopy in petrophysics

Arns, Christoph; Washburn, Kate; Callaghan, Paul T
Fonte: Society of Petrophysicists and Well Log Analysts (SPWLA) Publicador: Society of Petrophysicists and Well Log Analysts (SPWLA)
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
48.313403%
The characterization of reservoir quality necessitates a good understanding of the pore scale physics of the reservoir, in particular permeability of the formation, wettability, and fluid saturations. Classical interpretation of ID NMR logging data, a T2

‣ 3He NMR in porous media: Inverse Laplace transformation

Gazizulin, R. R.; Klochkov, A. V.; Kuzmin, V. V.; Safiullin, K. R.; Tagirov, M. S.; Yudin, A. N.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 21/09/2010 Português
Relevância na Pesquisa
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For the first time the inverse Laplace transform was applied for analysis of 3He relaxation in porous media. It was shown that inverse Laplace transform gives new information about these systems. The uniform-penalty algorithm has been performed to obtain the 3He relaxation times distribution in pores of clay sample. It is possible to obtain pores' sizes distribution by using applicable model. Keywords: inverse Laplace transform, uniform-penalty algorithm, liquid 3He, 3He, He3, He-3, helium-3, pulse nuclear magnetic resonance, clay, porous media.; Comment: 5 pages, 5 figures, docx

‣ Applications of controlled-flow laser-polarized xenon gas to porous and granular media study

Mair, R. W.; Wang, R.; Rosen, M. S.; Candela, D.; Cory, D. G.; Walsworth, R. L.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 09/11/2002 Português
Relevância na Pesquisa
48.69218%
We report initial NMR studies of continuous flow laser-polarized xenon gas, both in unrestricted tubing, and in a model porous media. The study uses Pulsed Gradient Spin Echo-based techniques in the gas-phase, with the aim of obtaining more sophisticated information than just translational self-diffusion coefficients. Pulsed Gradient Echo studies of continuous flow laser-polarized xenon gas in unrestricted tubing indicate clear diffraction minima resulting from a wide distribution of velocities in the flow field. The maximum velocity experienced in the flow can be calculated from this minimum, and is seen to agree with the information from the complete velocity spectrum, or motion propagator, as well as previously published images. The susceptibility of gas flows to parameters such as gas mixture content, and hence viscosity, are observed in experiments aimed at identifying clear structural features from echo attenuation plots of gas flow in porous media. Gas-phase NMR scattering, or position correlation flow-diffraction, previously clearly seen in the echo attenuation data from laser-polarized xenon flowing through a 2 mm glass bead pack is not so clear in experiments using a different gas mixture. A propagator analysis shows most gas in the sample remains close to static...

‣ The Narrow Pulse Approximation and long length scale determination in xenon gas diffusion NMR studies of model porous media

Mair, R. W.; Sen, P. N.; Hurlimann, M. D.; Patz, S.; Cory, D. G.; Walsworth, R. L.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 09/11/2002 Português
Relevância na Pesquisa
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We report a systematic study of xenon gas diffusion NMR in simple model porous media: random packs of mono-sized glass beads, and focus on three specific areas peculiar to gas-phase diffusion. These topics are: (i) diffusion of spins on the order of the pore dimensions during the application of the diffusion encoding gradient pulses in a PGSE experiment (breakdown of the 'narrow pulse approximation' and imperfect background gradient cancellation), (ii) the ability to derive long-length scale structural information, and (iii) effects of finite sample size. We find that the time-dependent diffusion coefficient, D(t), of the imbibed xenon gas at short diffusion times in small beads is significantly affected by the gas pressure. In particular, as expected, we find smaller deviations between measured D(t) and theoretical predictions as the gas pressure is increased, resulting from reduced diffusion during the application of the gradient pulse. The deviations are then completely removed when water D(t) is observed in the same samples. The use of gas also allows us to probe D(t) over a wide range of length scales, and observe the long-time asymptotic limit which is proportional to the inverse tortuosity of the sample, as well as the diffusion distance where this limit takes effect (~ 1 - 1.5 bead diameters). The Pade approximation can be used as a reference for expected xenon D(t) data between the short and long time limits...

‣ Tortuosity Measurement and the Effects of Finite Pulse Widths on Xenon Gas Diffusion NMR Studies of Porous Media

Mair, R. W.; Hurlimann, M. D.; Sen, P. N.; Schwartz, L. M.; Patz, S.; Walsworth, R. L.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 09/11/2002 Português
Relevância na Pesquisa
48.9426%
We have extended the utility of NMR as a technique to probe porous media structure over length scales of ~ 100 - 2000 micron by using the spin 1/2 noble gas 129Xe imbibed into the system's pore space. Such length scales are much greater than can be probed with NMR diffusion studies of water-saturated porous media. We utilized Pulsed Gradient Spin Echo NMR measurements of the time-dependent diffusion coefficient, D(t) of the xenon gas filling the pore space to study further the measurements of both the surface area-pore volume ratio, S/Vp, and the tortuosity (pore connectivity) of the medium. In uniform-size glass bead packs, we observed D(t) decreasing with increasing t, reaching an observed asymptote of ~ 0.62 - 0.65D0, that could be measured over diffusion distances extending over multiple bead diameters. Measurements of D(t)/D0 at differing gas pressures showed this tortuosity limit was not affected by changing the characteristic diffusion length of the spins during the diffusion encoding gradient pulse. This was not the case at the short time limit, where D(t)/D0 was noticeably affected by the gas pressure in the sample. Increasing the gas pressure, and hence reducing D0 and the diffusion during the gradient pulse served to reduce the previously observed deviation of D(t)/D0 from the S/Vp relation. The Pade approximation is used to interpolate between the long and short time limits in D(t). While the short time D(t) point lay above the interpolation line in the case of small beads...

‣ Transverse NMR relaxation as a probe of mesoscopic structure

Kiselev, Valerij G.; Novikov, Dmitry S.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
48.08295%
Transverse NMR relaxation in a macroscopic sample is shown to be extremely sensitive to the structure of mesoscopic magnetic susceptibility variations. Such a sensitivity is proposed as a novel kind of contrast in the NMR measurements. For suspensions of arbitrary shaped paramagnetic objects, the transverse relaxation is found in the case of a small dephasing effect of an individual object. Strong relaxation rate dependence on the objects' shape agrees with experiments on whole blood. Demonstrated structure sensitivity is a generic effect that arises in NMR relaxation in porous media, biological systems, as well as in kinetics of diffusion limited reactions.; Comment: 4 pages, 3 figures

‣ Anomalous diffusion coefficient in disordered media from NMR relaxation

Sitnitsky, A. E.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
48.459053%
Application of fractional calculus to the description of anomalous diffusion and relaxation processes in complex media provided one of the most impressive impulses to the development of statistical physics during the last decade. In particular the so-called fractional diffusion equation enabled one to capture the main features of anomalous diffusion. However the price for this achievement is rather high - the fractional diffusion coefficient becomes an involved function of a characteristic of the media (e.g., that of the radius of pores in the case of the porous one). Revealing this dependence from the first principles is one of the main problems in this field of science. Another one still remains that of extracting this dependence from the experiment. The latter problem is tackled in the present paper. Our aim is to provide detailed and pedagogical deriving the relationship of the fractional diffusion coefficient with experimentally observable value from nuclear magnetic resonance (NMR) spin-lattice relaxation data. The result obtained promotes the NMR relaxation method to become a powerful tool in solving the problem of experimental measuring the fractional diffusion coefficient. Also the merits and limitations of NMR relaxation method and pulsed-field gradient (PFG) NMR for the research of anomalous diffusion are compared and discussed.; Comment: LaTex...

‣ NMR studies of carbon dioxide sequestration in porous media

Hussain, Rehan
Fonte: University of Cambridge; Department of Chemical Engineering and Biotechnology Publicador: University of Cambridge; Department of Chemical Engineering and Biotechnology
Tipo: Thesis; doctoral; PhD
Português
Relevância na Pesquisa
89.44918%
Carbon dioxide (CO2) sequestration in the sub-surface is a potential mitigation technique for global climate change caused by greenhouse gas emissions. In order to evaluate the feasibility of this technique, understanding the behaviour of CO2 stored in geological rock formations over a range of length- and time-scales is crucial. The work presented in this dissertation contributes to the knowledge in this field by investigating the two-phase flow and entrapment processes of CO2, as well as other relevant fluids, in porous media at the pore- and centimetre-scales using a combination of lab-based nuclear magnetic resonance (NMR) experimental techniques and lattice Boltzmann (LB) numerical simulation techniques. Pulsed field gradient (PFG) NMR techniques were used to acquire displacement distributions (propagators) of brine flow through a model porous medium (100 ?m glass bead packing) before and after the capillary (residual) trapping of gas-phase CO2 in the pore space. The acquired propagators were compared quantitatively with the corresponding LB simulations. In addition, magnetic resonance imaging (MRI) techniques were used to characterise the extent of CO2 trapping in the bead pack. The acquired NMR propagators were compared to LB simulations applied to various CO2 entrapment scenarios in order to investigate the pore morphology in which CO2 becomes entrapped. Subsequently...

‣ A Comparison of Pore Size Distributions Derived by NMR and X-ray-CT Techniques

Arns, Christoph
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
48.18175%
High resolution micro-X-ray-CT data is used as a "gold standard" to define the morphology of a number of sandstones as well as a carbonate rock. From these micro-CT images the NMR responses to surface relaxation and restricted diffusion in the internal magnetic field are calculated numerically. The NMR response is decomposed into a distribution of relaxation times by an inverse Laplace transformation. By interpreting the relaxation time distributions in terms of relaxation and diffusion modes pore size distributions are derived from the NMR responses. The pore size distributions obtained from an interpretation of the NMR data are compared with corresponding measures derived directly from the X-ray-CT images.