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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Microfluidics for Steam Assisted Gravity Drainage and Petroleum Applications

de Haas, Thomas 11 July 2013 (has links)
Petroleum research is responsible for making previously unusable reservoirs economically viable and for limiting the environmental impact of petroleum development. Microfluidics, the study of fluid flow at the micro-scale, is predominantly used to study biological phenomena. Adapting microfluidics to study petroleum requires the use of materials and methods not commonly used. This thesis focuses on applying microfluidics to the study of petrochemical fluid flow at high-pressure and high-temperature. The first problem addressed is the study of fluids during alkaline steam assisted gravity drainage (alkaline SAGD). The addition of an alkaline additive is found to improve the bitumen production rate by 35-67%. Secondly, two high-pressure, high-temperature, solvent resistant microfluidic interfaces for glass chips are designed to be operated up to 140 bar and 70 degrees Celsius. Lastly, a novel method for fabricating solvent resistant microfluidic devices from Teflon film is demonstrated by measuring the viscosity of toluene-heavy oil blends.
2

Microfluidics for Steam Assisted Gravity Drainage and Petroleum Applications

de Haas, Thomas 11 July 2013 (has links)
Petroleum research is responsible for making previously unusable reservoirs economically viable and for limiting the environmental impact of petroleum development. Microfluidics, the study of fluid flow at the micro-scale, is predominantly used to study biological phenomena. Adapting microfluidics to study petroleum requires the use of materials and methods not commonly used. This thesis focuses on applying microfluidics to the study of petrochemical fluid flow at high-pressure and high-temperature. The first problem addressed is the study of fluids during alkaline steam assisted gravity drainage (alkaline SAGD). The addition of an alkaline additive is found to improve the bitumen production rate by 35-67%. Secondly, two high-pressure, high-temperature, solvent resistant microfluidic interfaces for glass chips are designed to be operated up to 140 bar and 70 degrees Celsius. Lastly, a novel method for fabricating solvent resistant microfluidic devices from Teflon film is demonstrated by measuring the viscosity of toluene-heavy oil blends.
3

Extinction Limits of Laminar Diffusion Counterflow Flames of Various Gaseous Fuels including Syngas and Biogas

Kwan, Timothy 29 November 2013 (has links)
This work investigates the extinction limits of laminar diffusion counterflow flames for various gaseous (methane, syngas, biogas) fuels using a high flow rate counterflow burner designed and built for this work. Equal momenta of the fuel and oxidizer streams were not maintained to provide data to check the fidelity of the numerical schemes and their chemical mechanisms at "non-standard" conditions. Strain rate values at extinction were obtained as a function of fuel mole fraction. Preliminary work with the new burner found that the methane extinction limit results were consistent with results from literature. The results provide insight into the extinction limit conditions of the aforementioned fuels. The strain rate was found to increase with increasing fuel mole fraction. Extinction limit results indicated that fuels with the highest concentration of hydrogen have the greatest extinction limit, which is believed to be attributed to the high diffusivity and reactivity of hydrogen.
4

Extinction Limits of Laminar Diffusion Counterflow Flames of Various Gaseous Fuels including Syngas and Biogas

Kwan, Timothy 29 November 2013 (has links)
This work investigates the extinction limits of laminar diffusion counterflow flames for various gaseous (methane, syngas, biogas) fuels using a high flow rate counterflow burner designed and built for this work. Equal momenta of the fuel and oxidizer streams were not maintained to provide data to check the fidelity of the numerical schemes and their chemical mechanisms at "non-standard" conditions. Strain rate values at extinction were obtained as a function of fuel mole fraction. Preliminary work with the new burner found that the methane extinction limit results were consistent with results from literature. The results provide insight into the extinction limit conditions of the aforementioned fuels. The strain rate was found to increase with increasing fuel mole fraction. Extinction limit results indicated that fuels with the highest concentration of hydrogen have the greatest extinction limit, which is believed to be attributed to the high diffusivity and reactivity of hydrogen.
5

The Evolution of Soot Morphology in Laminar Co-flow Diffusion Flames of the Surrogates for Jet A-1 and a Synthetic Kerosene

Kholghy, Mohammad Reza 20 November 2012 (has links)
An experimental study was performed to study soot formation and evolution in atmospheric, laminar, coflow, diffusion flames of Jet-A1, Synthetic Paraffinic Kerosene and their surrogates. Light extinction, rapid thermocouple insertion and thermophoretic sampling followed by transmission electron microscopy and atomic forced microscopy were used to obtain soot volume fraction profiles, temperature profiles and soot morphologies, respectively. Different soot evolution processes were observed on the flame centerline and on a streamline with a significantly different temperature history. Formation and agglomeration of the first soot particles are different on the two streamlines. Transparent liquid-like particles are produced in large volumes in the early regions of the flame centerline where T < 1500 K; these particles are undetectable by the extinction method with the wavelength of 632.8 nm. Most of the currently used computational soot models do not predict the liquid-like nature of nascent soot particles which has major effects on the modeling.
6

The Evolution of Soot Morphology in Laminar Co-flow Diffusion Flames of the Surrogates for Jet A-1 and a Synthetic Kerosene

Kholghy, Mohammad Reza 20 November 2012 (has links)
An experimental study was performed to study soot formation and evolution in atmospheric, laminar, coflow, diffusion flames of Jet-A1, Synthetic Paraffinic Kerosene and their surrogates. Light extinction, rapid thermocouple insertion and thermophoretic sampling followed by transmission electron microscopy and atomic forced microscopy were used to obtain soot volume fraction profiles, temperature profiles and soot morphologies, respectively. Different soot evolution processes were observed on the flame centerline and on a streamline with a significantly different temperature history. Formation and agglomeration of the first soot particles are different on the two streamlines. Transparent liquid-like particles are produced in large volumes in the early regions of the flame centerline where T < 1500 K; these particles are undetectable by the extinction method with the wavelength of 632.8 nm. Most of the currently used computational soot models do not predict the liquid-like nature of nascent soot particles which has major effects on the modeling.
7

Imaging the Mechanics of Hydraulic Fracturing in Naturally-fractured Reservoirs Using Induced Seismicity and Numerical Modeling

Zhao, Xueping 05 September 2012 (has links)
The primary objective of this study is to improve understanding of the mechanics of hydraulic fracturing in naturally-fractured reservoirs. The study focuses on enhancing the interpretation of hydraulic fracture-induced microseismic data using an S-wave Gaussian-beam method and numerical modeling techniques for interpretation. The S-wave Gaussian-beam method was comprehensively calibrated by synthetic and real data sets with different recording networks, and this showed the potential to retrieve additional microseismic data from hydraulic fracturing with linear receiver arrays. This approach could enhance current practice because a large number of induced events in these environments have very strong S-waves with P-wave amplitudes similar, or less than, background noise levels. The numerical study using the distinct element methods PFC2D and PFC3D was used to validate the understanding of the hydraulic fracturing mechanisms induced in laboratory and field fluid treatments in naturally-fractured reservoirs. This was achieved through direct comparison with the results of the geometry of hydraulic fractures and seismic source information (locations, magnitudes, and mechanisms) from both laboratory experiments and field observations. A suite of numerical models with fully-dynamic and hydro-mechanical coupling has been used to examine in detail the interaction between natural and induced fractures with the variations of the differential stresses and the orientations of the pre-fractures, and the relationship between the fluid front, the fracture tip, and the induced seismicity. The numerical results qualitatively agreed with the laboratory and field observations of the geometry of hydraulic fractures, confirmed the possible mechanics of new fracture development and their interactions with natural fractures, and illustrated the possible relationship between the fluid front and the fracture tip. The validated model could therefore help track the potential extent of induced fracturing in naturally-fractured reservoirs and the extent to which it can be detected by a microseismic monitoring array in order to assess the effectiveness of a hydraulic fracturing project.
8

Imaging the Mechanics of Hydraulic Fracturing in Naturally-fractured Reservoirs Using Induced Seismicity and Numerical Modeling

Zhao, Xueping 05 September 2012 (has links)
The primary objective of this study is to improve understanding of the mechanics of hydraulic fracturing in naturally-fractured reservoirs. The study focuses on enhancing the interpretation of hydraulic fracture-induced microseismic data using an S-wave Gaussian-beam method and numerical modeling techniques for interpretation. The S-wave Gaussian-beam method was comprehensively calibrated by synthetic and real data sets with different recording networks, and this showed the potential to retrieve additional microseismic data from hydraulic fracturing with linear receiver arrays. This approach could enhance current practice because a large number of induced events in these environments have very strong S-waves with P-wave amplitudes similar, or less than, background noise levels. The numerical study using the distinct element methods PFC2D and PFC3D was used to validate the understanding of the hydraulic fracturing mechanisms induced in laboratory and field fluid treatments in naturally-fractured reservoirs. This was achieved through direct comparison with the results of the geometry of hydraulic fractures and seismic source information (locations, magnitudes, and mechanisms) from both laboratory experiments and field observations. A suite of numerical models with fully-dynamic and hydro-mechanical coupling has been used to examine in detail the interaction between natural and induced fractures with the variations of the differential stresses and the orientations of the pre-fractures, and the relationship between the fluid front, the fracture tip, and the induced seismicity. The numerical results qualitatively agreed with the laboratory and field observations of the geometry of hydraulic fractures, confirmed the possible mechanics of new fracture development and their interactions with natural fractures, and illustrated the possible relationship between the fluid front and the fracture tip. The validated model could therefore help track the potential extent of induced fracturing in naturally-fractured reservoirs and the extent to which it can be detected by a microseismic monitoring array in order to assess the effectiveness of a hydraulic fracturing project.
9

Sol-gel synthesized nanomaterials for environmental applications

Yang, Xiangxin January 1900 (has links)
Doctor of Philosophy / Department of Chemical Engineering / Larry E. Erickson / Over the past decade, nanomaterials have been the subject of enormous interest. Their defining characteristic is a very small size in the range of 1-100 nm. Due to their nanometer size, nanomaterials are known to have unique mechanical, thermal, biological, optical and chemical properties, together with the potential for wide-ranging industrial applications. Here, we synthesized nanocrystalline metal oxides through the sol-gel process and used these materials as desulfurization adsorbents and photocatalysts. Deep desulfurization of fuels has received more and more attention worldwide, not only because of health and environmental consideration but also due to the need for producing ultra-low-sulfur fuels, which can only be achieved under severe operating conditions at high cost using hydrodesulfurization (HDS). Consequently, development of new and affordable deep desulfurization processes to satisfy the decreasing limit of sulfur content in fuels is a big challenge. Sol-gel derived Cu/Al[subscript]2O[subscript]3 and Zn/Al[subscript]2O[subscript]3 adsorbents have been demonstrated to be effective in the removal of thiophene from a model solution. Results showed that Cu[superscript]+ was the active site and thermal treatment under vacuum was critical for Zn/Al[subscript]2O[subscript]3 since a defective, less crystalline spinel led to stronger interaction between zinc ions and thiophene molecules in the adsorption process. The kinetic study suggested that most of the adsorption occurred in the first 30 min, and adsorption equilibrium was attained after 1.5 h. Both adsorbents showed good regenerative property. TiO2 is considered the most promising photocatalyst due to its high efficiency, chemical stability, non-toxicity, and low cost for degradation and complete mineralization of organic pollutants. However, the use of TiO[subscript]2 is impaired because it requires ultraviolet (UV) activation ([Lambda]<387 nm). The shift of optical response of TiO[subscript]2 from the UV to the visible light region would have a profound positive effect on the efficient use of solar energy in photocatalytic reactions. We shifted the optical response of TiO[subscript]2 and improved the photocatalytic efficiency through size modification and transition metal ion and nonmetal atom doping. Experimental results showed that C and V co-doped TiO[subscript]2 catalysts had much higher activity than commercial P25 TiO[subscript]2 towards the degradation of acetaldehyde under visible light irradiation. For the first time, we reported that activities were comparable in the dark and under visible light irradiation for co-doped TiO[subscript]2 with 2.0 wt% V. C and N co-doped TiO[subscript]2 exhibited higher activity for the degradation of methylene blue than pure TiO[subscript]2 under visible light and UV irradiation. Possible mechanisms were discussed based on the experimental results.
10

The Pore Structure of Indiana Limestone and Pink Dolomite for the Modeling of Carbon Dioxide in Geologic Carbonate Rock Formations

Freire-Gormaly, Marina 22 November 2013 (has links)
The primary objective was to predict the relative storage capacity of carbonate rocks relevant for carbon dioxide sequestration. To achieve this, a detailed pore scale characterization of model carbonate rocks, Indiana Limestone and Pink Dolomite, was conducted utilizing micro-computed tomography (microCT) data using pore network modeling and invasion percolation simulations. For the first time in literature, Pink Dolomite’s pore space characteristics were analyzed. A secondary objective was to compare thresholding techniques as applied to carbonates which exhibit dual porosity (porosity at multiple length scales). The analysis showed the sensitivity of existing methods to the thresholding technique, imaging method and material. Overall, the contributions of this work provide an assessment of two carbonates relevant for carbon capture and storage at the pore scale; and a preliminary assessment into thresholding dual porosity carbonates.

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