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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 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.

Since 1996, super-critical CO$_2$ has been injected at a rate of $\sim$0.85~Mt~yr$^{-1}$ into a pristine, saline aquifer at the Sleipner carbon capture and storage project. A suite of time-lapse, three-dimensional seismic reflection surveys have been acquired over the injection site. This suite includes a pre-injection survey acquired in 1994 and seven post-injection surveys acquired between 1999 and 2010. Nine consistently bright reflections within the reservoir, mapped on all post-injection surveys, are interpreted to be thin layers of CO$_2$ trapped beneath mudstone horizons. The areal extents of these CO$_2$ layers are observed to either increase or remain constant with time. However, volume flux of CO$_2$ into these layers has proven difficult to measure accurately. In addition, the complex planform of the shallowest layer, Layer 9, has proven challenging to explain using reservoir simulations. In this dissertation, the spatial distribution of CO$_2$ in Layer~9 is measured in three dimensions using a combination of seismic reflection amplitudes and changes in two-way travel time between time-lapse seismic reflection surveys. The CO$_2$ volume in this layer is shown to be growing at an increasing rate through time. To investigate CO$_2$ flow within Layer~9, a numerical gravity current model that accounts for topographic gradients is developed. This vertically-integrated model is computationally efficient, allowing it to be inverted to find reservoir properties that minimise differences between measured and modelled CO$_2$ distributions. The best-fitting reservoir permeability agrees with measured values from nearby wells. Rapid northward migration of CO$_2$ in Layer~9 is explained by a high permeability channel, inferred from spectral decomposition of the seismic reflection surveys. This numerical model is found to be capable of forecasting CO$_2$ flow by comparing models calibrated on early seismic reflection surveys to observed CO$_2$ distributions from later surveys. Numerical and analytical models are then used to assess the effect of the proximity of an impermeable base on the flow of a buoyant fluid, motivated by the variable thickness of the uppermost reservoir. Spatial gradients in the confinement of the reservoir are found to direct the flow of CO$_2$ when the current is of comparable thickness to the reservoir. Finally, CO$_2$ volume in the second shallowest layer, Layer~8, is measured using structural analysis and numerical modelling. CO$_2$ in Layer~8 is estimated to have reached the spill point of its structural trap by 2010. CO$_2$ flux into the upper two layers is now $\sim$40\% of total CO$_2$ flux injected at the base of the reservoir, and is increasing with time. This estimate is supported by observations of decreasing areal growth rate of the lower layers. The uppermost layers are therefore expected to contribute significantly to the total reservoir storage capacity in the future. CO$_2$ flow within Layer~9 beyond 2010 is forecast to be predominantly directed towards a topographic dome located $\sim$3~km north of the injection point. This dissertation shows that advances in determining the spatial distribution and flow of CO$_2$ in the sub-surface can be made by a combination of careful seismic interpretation and numerical flow modelling.

Orientador: Caio Gorla Nogueira / Resumo: Este trabalho apresenta um conjunto de técnicas estatísticas básicas aplicadas à modelagem de problemas de fluxo em meios porosos fraturados e de estabilidade de taludes, com o objetivo de identificar as variáveis explicativas mais influentes sobre a variabilidade das variáveis resposta. Diferentes planejamentos de experimentos foram utilizados para possibilitar a construção de metamodelos polinomiais representativos dos fenômenos estudados. Uma modificação do planejamento do tipo Box-Behnken é apresentada e foi proposta pelo autor para analisar problemas que envolvem elevado número de variáveis explicativas (e.g. 30). Os metamodelos, obtidos via método dos mínimos quadrados, são também chamados de superfícies de resposta ou modelos de regressão e são indispensáveis à verificação da sensibilidade das variáveis explicativas. O conjunto de técnicas mostrou- se muito eficaz na identificação das variáveis explicativas que provocaram efeitos mais significativos sobre a variável resposta. Evidenciou-se também, por meio dos exemplos de estabilidade de taludes tratados, a possibilidade de se quantificar incertezas com o uso de metamodelos suficientemente adequados, uma opção que pode ser bastante útil no processo de quantificação de incertezas de problemas que não possuem soluções analíticas simples. / Abstract: This paper presents a set of basic statistical techniques applied to the modeling of flow problems in fractured porous and slope stability media, aiming to identify the most influential explanatory variables on the response variables variability. Different designs of experiments were used to enable the construction of polynomial metamodels representative of the studied phenomena. A Box-Behnken type design modification is presented and was proposed by the author to analyze problems involving high number of explanatory variables (e.g. 30). The metamodels, obtained by the least squares method, are also called response surfaces or regression models and are indispensable for verifying the sensitivity of the explanatory variables. The set of techniques was very effective in identifying the explanatory variables that had the most significant effects on the response variable. It was also evidenced, through the examples of stability of treated slopes, the possibility of quantifying uncertainties using sufficiently adequate metamodels, an option that can be very useful in the process of quantifying uncertainty of problems that do not have simple analytical solutions. / Mestre

Experimental data convincingly show that viscosity of a fluid may change significantly with pressure. This observation leads to various generalizations of well-known models, like Darcy's law, Stokes' law or the Navier-Stokes equations, among others. This thesis investigates three such models in a series of three published papers. Their unifying topic is development of existence theory and finding a weak solution to systems of partial differential equations stemming from the considered models.