La experimentación y posterior modelización de los procesos de transporte y transferencia de calor y de masa en medios poroso saturados encuentra un gran número de dificultades que se derivan fundamentalmente de la heterogeneidad del propio medio, de la metodología de su parametrización estructural y física para asimilarlo a un medio continuo.Los objetivos planteados en la presente tesis se han orientado hacia un mejor conocimiento de la influencia de diversos parámetros estructurales del medio poroso, así como de las propiedades de las substancias que constituyen la matriz sólida y la fase fluida saturante, en las características de ebullición de un medio poroso inicialmente saturado, calentado por su frontera inferior y limitado por una capa superior del mismo líquido saturante.A tal fin, se ha estudiado la influencia de la estructura del medio poroso (granular o fibrilar) y de la naturaleza de la sustancia que constituye la matriz sólida sobre la permeabilidad del medio poroso al agua y a una solución acuosa de tensioactivo, de baja concentración. Así mismo se ha estudiado la influencia respecto a la conductividad y difusividad térmicas efectivas en régimen no estacionario. Por último, utilizando la misma variedad de medios porosos saturados, se estudia el proceso de ebullición hasta que se alcanzan condiciones de "dryout", y se analizan las consecuencias que resultan de la variación de la estructura física del medio poroso, de la naturaleza de la sustancia que constituye su matriz sólida y de las propiedades del fluido saturante.En lo referente a las características fluidodinámicas y térmicas de los medios porosos estudiados se ha podido concluir:- La adición de un tensioactivo al agua saturante del medio poroso produce un comportamiento diferente según la naturaleza del sólido: en caso de inorgánica (arena) ocasiona un aumento de la permeabilidad intrínseca, mientras que en caso de orgánica (fibras de algodón) produce una reducción tanto mayor cuanto menor es la porosidad del medio poroso. Las causas de este diferente comportamiento, son las notables diferencias de absorción del tensioactivo según el tipo de sólido (orgánico o inorgánico) y la mejora substancial de la humectación de la superficie del sólido inorgánico por el fluido lo que activa la eficacia de desplazamiento de toda fase no acuosa adsorbida o retenida entre partículas.- La difusividad térmica efectiva promediada espacialmente tiende al valor de la difusividad del componente del medio poroso de menor difusividad térmica a medida que transcurre el tiempo de calentamiento.- La difusividad térmica efectiva de los medios porosos saturados en los que &#61548;s / &#61548;l < 1 se aproxima a la de la fase líquida; en los medios para los que &#61548;s / &#61548;l >> 1, dicha difusividad térmica efectiva es un grado de orden superior a la de la fase líquida.- La adición de tensioactivo a la fase líquida saturante provoca la disminución de la conductividad térmica efectiva de medio poroso saturado en aquellos en que la fase sólida es granular e inorgánica.En lo referente al proceso de calentamiento de un medio poroso saturado hasta ebullición-"dryout" de su fase líquida se ha descrito un modelo físico de comportamiento de los diferentes medios porosos que comporta las siguientes fases:i) Calentamiento del medio hasta la temperatura de saturación de su fase líquida, con evidente aumento de volumen de las fases sólida y líquida por dilatación térmica.ii) Proceso de evaporación con formación de una capa bifásica cuya frontera superior se desplaza a la velocidad del frente de vapor. Simultáneamente se produce una disminución de la presión fluidoestática en la frontera de la capa bifásica, lo que se traduce en una reducción del reflujo de líquido hacia la placa calefactora.iii) Total desaturación de la entrefase medio poroso-placa calefactora al recibir por reflujo menos líquido del que es capaz de evaporar la placa calefactora. Aparición del "dryout" y elevación progresiva de la temperatura de la placa.iv) Aparición, en algún caso, de un fenómeno de basculamiento de la fase líquida desde la capa subenfriada a la zona desaturada del medio poroso. / A large number of difficulties are found in the experimentation and later modelization of transport and transfer heat and mass process in saturated porous media, which basically derive from the heterogeneity of the medium, the methodology of structural and physic parameterization to assimilate it to a continuous medium.The raised aims in this doctoral thesis have been directed towards a better knowledge of the influence of several structural parameters of the porous medium, as well as of the properties of the solid matrix and the saturating fluid phase, in the characteristics of boiling of an initially saturated porous medium, heated by its lower boundary and limited by an upper layer of the same saturating liquid.For this, the influence of the structure of the porous medium (granular or fibrous) and the nature of the solid matrix on the permeability to water and to a surfactant solution of lower concentration have been studied. The influence in relation to effective thermal conductivity and diffusivity in unstationary regime has also been studied. Finally, the boiling process until to achieve dryout conditions has been studied, and the consequences result from the variation of the physical structure of the porous medium, the nature of the solid matrix and the properties of the saturating fluid have been analyzed.About the fluid dynamic and thermal characteristics of the porous media studied, the thesis concludes that:- The addition of a surfactant to the saturating water of the porous medium produces a different behaviour depending on the nature of the solid: in inorganic matrix (sand) occasions an increase in the intrinsic permeability, whereas in organic matrix (cotton fibres) produces a decrease as greater as smaller is the porosity of the porous medium. The reasons of this different behaviour are the notable differences of absorption of the surfactant depending on the sort of solid matrix (organic or inorganic) and the important increase of the wetting of the inorganic solid's surface by the fluid activating the displacement of all adsorbed or retained not watery phase between particles.- The spatially averaged effective thermal diffusivity tends to the value of the diffusivity of the component of the porous medium with lower thermal diffusivity throughout the boiling process.- The effective thermal diffusivity of the saturated porous media which have &#61548;s / &#61548;l < 1 approaches to of the liquid phase; in the media with &#61548;s / &#61548;l >> 1, the effective thermal diffusivity is a grade of upper order to the of liquid phase.- The addition of surfactant to the saturating liquid phase gives rise to the decrease of the effective thermal conductivity of the saturated porous medium with granular and inorganic solid phase. A physical model of behaviour of the different saturated porous media concerning heating process until to achieve dryout conditions has been described considering the next phases:i) Heating of the medium until the saturation temperature of its liquid phase, with evident increase of volume of the solid and liquid phases by thermal dilatation.ii) Evaporation process with creation of a biphasic layer whose upper boundary displaces to the velocity of the vapour front. Simultaneously a decrease of the fluid static pressure in the boundary of the biphasic layer is produced, what result in a reduction of the reflux of liquid towards the heating plate.iii) Total unsaturation of the porous medium-heating plate interphase caused by to receive less liquid by reflux that the heating plate is capable of evaporating.iv) Appearance, in some case, of a fast phenomenon of turn upside down of the liquid phase from subcooled layer to the unsaturated zone of the porous medium.

This thesis provides an introduction to and analysis of the problem of determining nuclear magnetic resonance (NMR) relaxation times of porous media by using the so-called Carr-Purcell-Meiboom-Gill (CPMG) technique. We introduce the principles of NMR, the CPMG technique and the signals produced, porous effects on the NMR relaxation times and discuss various numerical methods for the inverse problem of extracting the relaxation times from CPMG signals. The numerical methods for solving Fredholm integral equations of the first kind are sketched from a series expansion perspective. A method of using arbitrary constituent functions for improving the performance of non-negative least squares (NNLS) is developed and applied to several synthesized data sets and real experimental data sets of saturated porous glass gels. The data sets were obtained by the author of this thesis and the experimental procedure will be presented. We discuss the imperfections in the assumptions on the physical and numerical models, the numerical schemes, and the experimental results, which may lead to new research possibilities.

The concept of using dynamic excitation to enhance fluid flow in a porous medium began to arise in the mid-twentieth century. The initial spark of interest in the subject spurred numerous laboratory investigations throughout the latter half of the twentieth century to identify the mechanisms at work, and to develop field techniques for practical application of the technology. Several prominent laboratory and field studies have been published; however, there are some deficiencies that facilitate the need for further investigation. Groundwater flow and soil dynamics are two distinct areas of research. There is little in common between the two subjects and there is no consideration of soil dynamic properties in any of the reviewed papers. This study will attempt to bridge the gap between these two areas of research. The objective of this research is to attempt to determine how dynamic excitation of a soil matrix affects saturated single-phase fluid flow. This question is investigated through an extensive literature review of previous studies conducted on this topic, as well as through experimentation designed to replicate the mechanisms responsible for this phenomenon. Experimentation on coarse soil samples is conducted using a modified Stokoe-type resonant column device that allows a quantification of the effects of torsional and axial excitation, frequency of vibration, and strain level. This type of testing in the both the torsional and axial mode has never been conducted before using a resonant column; the Poisson ratios computed using the complimentary data has never been published in the literature.

This thesis provides an introduction to and analysis of the problem of determining nuclear magnetic resonance (NMR) relaxation times of porous media by using the so-called Carr-Purcell-Meiboom-Gill (CPMG) technique. We introduce the principles of NMR, the CPMG technique and the signals produced, porous effects on the NMR relaxation times and discuss various numerical methods for the inverse problem of extracting the relaxation times from CPMG signals. The numerical methods for solving Fredholm integral equations of the first kind are sketched from a series expansion perspective. A method of using arbitrary constituent functions for improving the performance of non-negative least squares (NNLS) is developed and applied to several synthesized data sets and real experimental data sets of saturated porous glass gels. The data sets were obtained by the author of this thesis and the experimental procedure will be presented. We discuss the imperfections in the assumptions on the physical and numerical models, the numerical schemes, and the experimental results, which may lead to new research possibilities.

The concept of using dynamic excitation to enhance fluid flow in a porous medium began to arise in the mid-twentieth century. The initial spark of interest in the subject spurred numerous laboratory investigations throughout the latter half of the twentieth century to identify the mechanisms at work, and to develop field techniques for practical application of the technology. Several prominent laboratory and field studies have been published; however, there are some deficiencies that facilitate the need for further investigation. Groundwater flow and soil dynamics are two distinct areas of research. There is little in common between the two subjects and there is no consideration of soil dynamic properties in any of the reviewed papers. This study will attempt to bridge the gap between these two areas of research. The objective of this research is to attempt to determine how dynamic excitation of a soil matrix affects saturated single-phase fluid flow. This question is investigated through an extensive literature review of previous studies conducted on this topic, as well as through experimentation designed to replicate the mechanisms responsible for this phenomenon. Experimentation on coarse soil samples is conducted using a modified Stokoe-type resonant column device that allows a quantification of the effects of torsional and axial excitation, frequency of vibration, and strain level. This type of testing in the both the torsional and axial mode has never been conducted before using a resonant column; the Poisson ratios computed using the complimentary data has never been published in the literature.

The behavior of bubbles migrating in porous media is a critical factor in several soil remediation operations such as in situ air sparging, supersaturated water injection, bioslurping, trench aeration and up-flow operation of moving bed sand filters as well as in the oil and gas industry. Groundwater aquifers are constantly polluted by human activity and a common threat to fresh water is the contamination by non-aqueous phase liquids (NAPL). In many NAPL removal technologies, gas bubbles carrying NAPL residuals move upwards through the water-saturated porous media and thus play an essential role in contaminant recovery. The mobilization of the residual oil blobs in oil reservoirs is another important application for rising bubbles in porous media. After an oil field is waterflooded, a significant fraction of oil, referred to as waterflood residual oil, remains trapped. A potential mechanism to recover this residual oil is the mobilization of oil by gas bubbles moving upwards in water-wet systems. The main focus of this work was to measure the velocity of bubbles of various lengths during their migration through a water-wet porous medium. Experiments were conducted in a saturated glass micromodel with different test liquids, air bubbles of varying lengths and different micromodel elevation angles. More than a hundred experimental runs were performed to measure the migration velocity of bubbles as a function of wetting fluid properties, bubble length, and micromodel inclination angle. The results showed a linear dependency of the average bubble velocity as a function of bubble length and the sine of inclination angle of the model. Comparisons were made using experimental data for air bubbles rising in kerosene, Soltrol 170 and dyed White Oil. The calculated permeability of the micromodel was obtained for different systems assuming the effective length for viscous dissipation is equal to the initial bubble length. It was found that the calculated permeability had an increasing trend with increasing bubble length. Laboratory visualization experiments were conducted for air bubbles in White Oil (viscosity of 12 cP) to visualize the periodic nature of the flow of rising bubbles in a pore network. The motion of the air bubbles in saturated micromodel was video-recorded by a digital camera, reviewed and analyzed using PowerDVD ™11 software. An image of a bubble migrating in the porous medium was obtained by capturing a still frame at a specific time and was analyzed to determine the bubble shape, the exact positions of the bubble front and bubble tail during motion and, thus, the dynamic length of the bubble. A deformation in the shape of the bubble tail end was observed for long bubbles. The dynamic bubble lengths were larger than the static bubble lengths and showed an increasing trend when increasing the angle of inclination. The dynamic bubble lengths were used to recalculate the bubble velocity and permeability. A linear correlation was found for the average bubble velocity as a function of dynamic bubble length. Numerical simulation was performed by modifying an existing MATLAB® simulation for the rise velocity of a gas bubble and the induced pressure field while it migrates though porous media. The results showed that the rise velocity of a gas bubble is affected by the grid size of the pore network in the direction perpendicular to the bubble migration. In reality, this effect is demonstrated by the presence of other bubbles near the rising bubble in porous media. The simulation results showed good agreement with experimental data for long bubbles with high velocities. More work is required to improve the accuracy of simulation results for relatively large bubbles.

Elemental sulphur (S0) is produced from processing bitumen from the oil sands region, Alberta. Long term storage of this S0 is under consideration. The objective of the current study was to determine the controls on water migration in variably saturated S0 blocks. Based on visual observations of S0 blocks, they were characterized as a hydrophobic fractured porous media. Thus, measurements of the hydraulic characteristics, including porosity (n) and hydraulic conductivity (K) of the matrix and the fractured media, were undertaken. These data were used to create characteristic relationships of unsaturated K (Kunsat) and volumetric moisture content (è) change with change in positive injection pressure (Ø).<p>Analyses showed that the mean total matrix n (nm) was 0.094 ± 0.035 (n = 280), the mean n available for water migration (na) was 0.065 ± 0.044 (n = 8) and the mean (geometric) K for the matrix was 2.0 x 10-6 ± 2.1 x 10-6 ms-1. In the case of vertical fractures, the aperture frequencies were measured to be 2.5, 10.0 and 21.0 m-1 for fractures with apertures > 1.4, 1.4 to 0.6 and < 0.6 mm respectively while the frequency of horizontal fractures, were measured to be 1.7 and 3.7 m-1 for with apertures > 1.4, and < 1.4 mm respectively. The fracture n (nf) was determined to be 0.0135. è Ø relationships were determined for both the fractured and non fractured media. From these plots, water entry values of 9 mm and 1 m were determined for the fracture pore space and the matrix pore space, respectively.<p>Simulations of packer tests resulted in a bulk saturated K (Kb) values ranging from 8.5 x 10-5 to 2 x 10-4 ms-1 above 9 m depth and 3 x 10-6 to 1.5 x 10-5 ms-1 below 9 m depth. Coupled Kunsat Ø and è Ø relationships were used to conceptually describe water migration in S0 blocks under different precipitation and mounding conditions. These plots also showed that the Kb is dominated by the fractures.

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