The main objective of this thesis was to study the effects of crude oil extracts on intertidal sediment communities. The approach was to focus on community structure and investigate the impact of a specific perturbation, crude oil extracts, relating to hypothetical oil spill situations. Both the impact of different disturbances on the same benthic community (i.e. with uniform structure) and the impact of the same disturbance on differently structured benthic communities were investigated. The effects on number of species, distribution of individuals between species and diversity were analysed, as well as recovery mode (trajectory of the system in time) and species arrival. The effects of different levels of a disturbance on an intertidal community were assessed, using water soluble fractions of crude oil (WSF) and two different concentrations of formaldehyde. The WSF had very little effect on community structure and recovery of the benthic community was prompt. The effects of the different concentrations of formaldehyde on the benthic community were indistinguishable: both concentrations had dramatic immediate effects. The relation between complexity and stability in benthic communities was evaluated by first setting-up two communities of different complexity using the equilibrium theory of island biogeography. After these different communities were established they were subjected to the effects of oil and dispersant. The impact of this perturbation on the two communities with different complexity was analysed both in terms of structure (as above) and functional level, through the analysis of oxygen uptake in the different communities. Although there was an indication that the oil had a depressing effect on the structure of both community types, it was not clear which species were most affected by the treatment. Individual comparisons between the two differently-structured treated communities and their controls were undertaken.

In this Masters dissertation, various doses of solubulized crude F4 fimbrial protein in conjunction with the adjuvants CpG ODN and porcine â-defensin 1 (pBD-1) were used to enhance the F4-specific intestinal immune response against Enterotoxigenic Escherichia coli (ETEC) F4 in post-weaned pigs. Using the mechanically shearing method we isolated the F4 fimbrial protein of ETEC with a molecular weight of 26 kDa. We verified this using a Western blot probed with a rabbit anti-F4 fimbrial antibody. Binding of the F4 fimbrial protein to the F4 receptor (F4R), present on the brush border of the villi in the small intestine of pigs, was demonstrated using an in vitro villus adhesion assay (IVVA). To demonstrate specificity rabbit polyclonal and mouse monoclonal anti-F4 antibodies, or the F4 protein were used to inhibit the adhesion of ETEC F4ac to F4R positive (F4Rpos) villi. <p>To examine immunogenicity of the 500 micrograms (ìg) of the F4 were administered into surgically created jejunal gut-loops in pigs. Three weeks later Peyers patches (PP) from immunized and control loops as well as gut-wall tissue were analyzed for their F4-specific antibody secreting cells (ASCs) by a modified enzyme linked immunosorbent spot (ELISPOT) assay. The F4-specific immune response in the serum was analyzed by an enzyme linked immunosorbant assay (ELISA). High numbers of F4-specific ASCs were isolated from the loops of pigs that contained high levels of the F4R. Conversely nominal or low numbers of F4-specific ASCs were found in loops of pigs expressing low levels of the F4R or no F4R (F4Rneg). The IVVA was used to categorize the pigs into either F4Rpos or F4Rneg animals. <p>Next three different concentrations of the crude F4 protein 50, 250, and 500 µg in the loops of individual pigs were used to analyze if dose affected the F4-specific immune response. Interestingly dose had no effect on the magnitude of the response. Therefore we hypothesized that the F4-specific immune response in the loops could be enhanced through the use of the adjuvants CpG ODN 2007 and pBD-1. The F4 protein was co-administered with either CpG ODN 2007 or pBD-1 and immune responses were assessed after 3 weeks. However neither CpG ODN 2007 nor PBD-1 at the doses used made an improvement in the immune response. Thus, these results demonstrated that the expression level of the F4R was the most important parameter for eliciting of the local immune response against the F4 protein. Furthermore our studies revealed that both F4Rneg and F4Rpos pigs responded to F4 immunization, however the former respond only nominally to F4-immunization in the loops. Moreover, an inverse relationship existed between the level of the F4-specific IgG in the serum and the F4-specific immune response seen in the loops. Thus our findings have important implications for oral vaccination using fimbrial based antigens (Ags) that utilize a receptor for their immunogenicity. Our results indicate that only animals with high levels of enterocyte F4R will have the ability to elicit high levels of protective F4-specific anti-fimbrial antibodies in their intestine after oral immunization. Therefore unless an effective adjuvant is available, animals with low to moderate levels of the fimbrial receptor in their small intestine will mount only weak immune responses making herd immunity after vaccination currently unattainable.

In this Masters dissertation, various doses of solubulized crude F4 fimbrial protein in conjunction with the adjuvants CpG ODN and porcine â-defensin 1 (pBD-1) were used to enhance the F4-specific intestinal immune response against Enterotoxigenic Escherichia coli (ETEC) F4 in post-weaned pigs. Using the mechanically shearing method we isolated the F4 fimbrial protein of ETEC with a molecular weight of 26 kDa. We verified this using a Western blot probed with a rabbit anti-F4 fimbrial antibody. Binding of the F4 fimbrial protein to the F4 receptor (F4R), present on the brush border of the villi in the small intestine of pigs, was demonstrated using an in vitro villus adhesion assay (IVVA). To demonstrate specificity rabbit polyclonal and mouse monoclonal anti-F4 antibodies, or the F4 protein were used to inhibit the adhesion of ETEC F4ac to F4R positive (F4Rpos) villi. <p>To examine immunogenicity of the 500 micrograms (ìg) of the F4 were administered into surgically created jejunal gut-loops in pigs. Three weeks later Peyers patches (PP) from immunized and control loops as well as gut-wall tissue were analyzed for their F4-specific antibody secreting cells (ASCs) by a modified enzyme linked immunosorbent spot (ELISPOT) assay. The F4-specific immune response in the serum was analyzed by an enzyme linked immunosorbant assay (ELISA). High numbers of F4-specific ASCs were isolated from the loops of pigs that contained high levels of the F4R. Conversely nominal or low numbers of F4-specific ASCs were found in loops of pigs expressing low levels of the F4R or no F4R (F4Rneg). The IVVA was used to categorize the pigs into either F4Rpos or F4Rneg animals. <p>Next three different concentrations of the crude F4 protein 50, 250, and 500 µg in the loops of individual pigs were used to analyze if dose affected the F4-specific immune response. Interestingly dose had no effect on the magnitude of the response. Therefore we hypothesized that the F4-specific immune response in the loops could be enhanced through the use of the adjuvants CpG ODN 2007 and pBD-1. The F4 protein was co-administered with either CpG ODN 2007 or pBD-1 and immune responses were assessed after 3 weeks. However neither CpG ODN 2007 nor PBD-1 at the doses used made an improvement in the immune response. Thus, these results demonstrated that the expression level of the F4R was the most important parameter for eliciting of the local immune response against the F4 protein. Furthermore our studies revealed that both F4Rneg and F4Rpos pigs responded to F4 immunization, however the former respond only nominally to F4-immunization in the loops. Moreover, an inverse relationship existed between the level of the F4-specific IgG in the serum and the F4-specific immune response seen in the loops. Thus our findings have important implications for oral vaccination using fimbrial based antigens (Ags) that utilize a receptor for their immunogenicity. Our results indicate that only animals with high levels of enterocyte F4R will have the ability to elicit high levels of protective F4-specific anti-fimbrial antibodies in their intestine after oral immunization. Therefore unless an effective adjuvant is available, animals with low to moderate levels of the fimbrial receptor in their small intestine will mount only weak immune responses making herd immunity after vaccination currently unattainable.

This paper is intended to better understand the effects of speculation on crude oil prices. While speculation has many benefits such as increasing market liquidity and bearing market risks that other wish to offset, speculation can also create unwanted market volatility and economic bubbles. During the past decade, crude oil prices have been extremely volatile causing increased controversy between investors and regulators regarding the role that oil speculation has played in the price of crude oil. This report examines the relationship between crude oil spot and futures prices to determine the role arbitragers, speculators, and hedgers have had in crude oil pricing. / text

Computational Fluid Dynamics (CFD) is used in this study to assess the influence of temperature-dependent oil viscosity and density on the flow of oil up the well, and therefore the amount of insulation required. CFD is a difficult tool to apply to flows where the grid aspect ratio is as high as it needs to be to accommodate the full length of an oil well with a realistic number of grid points. Each model was therefore intensive in terms of computational effort and time. This study shows that by allowing oil viscosity and density to vary with temperature in a 2150 m vertical well with no insulation, the production output is significantly affected. The drop in production output is approximately 3% when oil viscosity varies with temperature, but when coupled with temperature-dependent density the loss in production increases to 22%. Ten CFD models, each with a different value of insulation heat transmission coefficient lying in the range 0.35 Wm^-2K^-1 to 16900 Wm^-2K^-1, are used to establish the temperature drop between riser inlet and outlet. The results obtained allow an operator to select an appropriate insulation based on the allowable temperature drop up the well, assuming all other properties are equal. The completion fluid region is situated outside the oil flow, tubing and insulation. The fluid is stationary which suggests that natural convection currents are present. Seven CFD models with annulus heights ranging from 1 m to 64 m are used to detect these currents, and assess the effectiveness of water as an insulating completion fluid. This thesis establishes that the natural convection currents do not split into multiple cells, but remain mono-cellular when the Grashof number is approximately 1x10⁸ and the Prandtl number is 2.3. This work also shows that heat loss due to natural convection from the completion fluid is an important contributory factor to the overall heat loss from a well, dependent on the well height.

No description available.

Made available in DSpace on 2018-08-01T21:36:53Z (GMT). No. of bitstreams: 1 tese_10765_Dissertação_final_Rayza.pdf: 2180620 bytes, checksum: 5e88e543a5adef7347618d2eef3cfb62 (MD5) Previous issue date: 2017-03-27 / A calibração multivariada associada à técnica de infravermelho é uma alternativa aos métodos tradicionais para determinação de parâmetros físico-químicos em petróleo. Entretanto, o modelo multivariado construído é aplicável somente para o instrumento no qual os espectros foram obtidos. A transferência de calibração de modelos multivariados é de fundamental importância para a indústria petrolífera, levando-se em conta que aumenta a aplicabilidade de modelos e permite estimar com rapidez e com poucos gastos diversas propriedades físico-químicas. Este trabalho foi dividido em duas seções: a primeira é dedicada à avaliação modelos de transferência entre dois instrumentos de infravermelho a região média (MIR) para modelos PLS (mínimos quadrados parciais) e OPLS (projeções ortogonais em estruturas latentes); e a segunda visa aplicar a transferência PDS (padronização direta por partes) a modelos PLS para predição de densidade API, TIAC (temperatura de início de aparecimento de cristais), NAT (número de acidez total) e NAN (número de acidez naftênica). Dentre os métodos quimiométricos SBC (correção de declive e viés), FR (recalibração total), DS (padronização direta) e PDS avaliados para previsão de densidade API, o modelo de transferência PDS aplicado ao modelo OPLS resultou na melhor capacidade preditiva (RMSEP de 1,48). A aplicação direta de PDS a um modelo PLS original conta com a vantagem de aproveitar modelos já consolidados, e os resultados da primeira seção indicam que isto é uma possibilidade. Na segunda seção, as propriedades API, TIAC, NAT e NAN foram modeladas e validadas por PLS para o instrumento primário. Espectros secundários, diferentes daqueles da primeira seção, passaram por uma interpolação polinomial a fim de igualar as variáveis às do instrumento primário, antes da aplicação da transferência PDS. Os espectros transferidos e processados por airPLS, técnica iterativa adaptativa, se tornaram indistiguíveis por PCA (análise por componentes principais) dos espectros primários. A técnica de PDS associada a modelos PLS mostrou-se promissora, especialmente sendo capaz de estimar com boa exatidão o valor da densidade API de amostras de petróleo classificadas como medianas.

Crude oil leakages often give rise to in situ contamination with both oil and salt. In this study, the biodegradation of model alkanes and of saturated hydrocarbons in whole crude oil by hydrocarbon-degrading bacteria was investigated at different salt (NaCl, KCl, Na2SO4) concentrations. Changes in cell surface hydrophobicity at different NaCl concentrations were also investigated. The results show that with increasing NaCl concentration, the lag phase for strain growth on hydrocarbons was prolonged; however, the total degradation efficiency was not influenced greatly. The formation of different sizes of cell aggregates at different salt concentrations indicated that salt could indirectly influence mass transfer of hydrocarbons from the medium to the interior of the cells. The results also showed that KCl had a less inhibitory effect on biodegradation than NaCl, and changes of Na2SO4 concentration did not greatly affect biodegradation. In addition, cell surface hydrophobicity increased with increasing NaCl concentration when the cultures were grown on hydrocarbons.

Crude oil is a complex mixture of aromatic and aliphatic hydrocarbons of diverse molecular weight. In spite of its high hydrophobicity and toxicity, crude oil is a rich source of carbon for microorganisms. It has been proposed that microbial metabolism contributes to petroleum physicochemical characteristics, as highly specialized microorganisms are adapted to its extreme conditions. Deciphering these unique microbiomes will allow more in-depth characterization of crude oil and better understand its chemistry. The general aim of this study is to characterize the unique microbial communities of crude oil through a comparative metagenomics approach. I performed a survey of worldwide crude oil metagenomes in literature and databases. I identified 48 metagenomics datasets from five countries. The Comparative analysis of these metagenomes allowed us to identify how Methanogens are predominant in the North-American crude oil, being Methanoculleus and Methanosaeta the dominant genera in Canada and Methanothermococcus the predominant genus in the United States oil fields. In the case of Nigeria crude oil, Marinobacterium and Parvivaculum were the two dominant genera. In the case of Thailand, the dominant genus Thermus reflected the high-temperature environment of that oil field. Finally, metagenomes from China were the most diverse, reflecting the heterogeneity of the oil fields from that country. I generated metagenomics data from 27 Saudi Arabian crude oil samples originated in 6 different oil fields. As no crude oil metagenome has been reported yet for the Arabian Peninsula, the information provided in this dissertation is contributing towards a complete worldwide characterization of crude oils. Two genera, Peanibacilus and Thermospira, are proposed as the taxonomic markers for the set of Saudi crude oil analyzed. In this thesis I elucidated the structure of microbial communities in crude oils globally, suggesting that it may reflect the geological history of crude oils. This study sheds light on the importance of microorganisms for understanding petroleum geobiology. These findings suggest that it is possible to identify the distinctive microbiota associated with specific types of crude oil according to its location. The results presented here set the basis for developing novel methodologies for crude oil identification based on a microbial fingerprinting approach.

A major problem faced by the petroleum industry is the deposition of wax during the pumping of waxy crude oils. This precipitation occurs at “normal” temperature, typically 20-30°C in Libya. It could occur during the journey from well to terminal through hundreds of miles of pipelines. This kind of transportation is expensive in terms of pumping costs. The pumping has to be continuous; otherwise wax can build up in the pipeline, reducing the pumping or even stopping it. The property that defines this characteristic is the yield stress which depends on wax concentration and cooling rate. The build-up of paraffin and asphaltenes can lead to serious problems in formation, tanks, and pipelines. Blockages can be expensive and time-consuming to deal with; this is precisely the topic of this research. For this research, model and real waxy crude oils are formulated and their rheology systematically measured under various cooling rates to determine the yield stress. A pipeline loop has been designed to measure the start-up pressure of stagnant oil which has been allowed to precipitate wax. The start-up pressure and the thickness of deposited wax are used in a simple mathematical model to calculate the yield stress. This research thus provides two independent means of predicting the yield stress. This research studied three different waxy crude oils. An MCR-301 Anton Paar rheometer was used to measure the rheology of the oils, and a pipeline rig was used to obtain the start-up pressure to calculate the yield stress of each type of oil after different stoppage times. Also, the thickness of the precipitated wax is measured to calculate the yield stress precisely. The data show that the layer thickness has significant effect on the yield stress and start-up pressures and corresponding yield flow stresses have been found to underpin the crystallisation process of the wax and slow cooling rate produce stronger structures requiring higher stresses to fracture and induce flow. Also, longer shutdown times make these structures even stronger and therefore require even larger stresses for flow to commence.