Dissertations / Theses on the topic 'Oil erosion'

The purpose of this study was to investigate the role of soil erosion as a factor in lake pollution and in particular the transport of phosphorus from field soils to streams and lakes in association with mobile sediment. Four land uses were selected as representative of the Slapton Ley catchment area to investigate the levels of phosphorus in the soil. The surface soil samples from the selected land use areas were analysed to determine the water-soluble phosphorus level in solution and exchangeable phosphorus level in sediment. Twelve experimental plots were studied in order to assess the erosional effects of overland flow and thus to determine the level of phosphorus from different land uses which may be influencing the eutrophication of the lake. It was concluded that slope angle, vegetation cover, surficial soil properties, animal influence and agricultural practice are the main factors influencing sediment transportation by overland flow. Estimated results for the agricultural fields indicated that the actual phosphorus loss to the Ley is always greater in sediment than solution and actual phosphorus loss in sediment is greater in arable (root) and cereal than in grass. The point water samples (136) from 13 different sources were grouped. Mean value of phosphorus concentration from the point sources indicated that the agricultural land uses such as arable and cereal provide 2 times more exchangeable phosphorus attached to sediment than the other land uses whereas farm and sewage provided 5 times more soluble phosphorus in water than other sources. Phosphorus concentration during peak discharge was examined for the Cara catchment. The results indicated that the ratio of phosphorus concentration in suspended sediment to phosphorus concentration in water is 240: 0.3 and that there is a linear relationship between phosphorus in water and phosphorus in sediment during the peak discharge. Sediment phosphorus levels in the marsh area were also examined. The results indicated that the top layers of the marsh sediment particularly at the surface, have higher phosphorus concentration than the lower layers and that there are higher levels in sediment than in water. From these results the conclusion was drawn that the soluble phosphorus in water is at highest concentration in sewage works effluent. However this effluent contributes a small proportion of phosphorus load to the Ley compared with the arable (root), cereal and grass lands in the catchment. Agricultural sources, particularly arable sources such as root and cereal play an important role on soil erosion as a factor in lake pollution and in particular in the transport of phosphorus from field soils to streams and lakes in association with mobile sediment in the Slapton Ley catchment.

Erosion-corrosion is a destructive process which can be encountered in the oil and gas industry when carbon steel pipelines transport sand particles in CO2-containing salt water and hydrocarbons. The high degradation rates attributed to this mechanism can create increased challenges to project economy and operation where material integrity, accurate corrosion rate prediction and long term performance are key concerns. This thesis presents a project with a firm foundation in practical engineering problems, supported by strong generic engineering science which holds wider applications. The research focuses on understanding and inhibiting the degradation processes occurring on a North Sea offshore facility which had experienced a number of unexpected failures and reportedly high degradation rates between 2005 and 2010. An empirical erosion-corrosion model is developed for the facility to provide accurate assessment of degradation rate. The prediction tool is subsequently compared to commercially available CO2 corrosion models and validated using inspection data. An assessment of the corrosion inhibition strategy on the facility and the screening of numerous corrosion inhibitors are conducted through gravimetric analysis and insitu AC/DC electrochemical techniques in static and dynamic conditions. The research discovers a more efficient chemical for controlling degradation processes on the facility whilst highlighting the ability of electrochemical techniques to help understand inhibition mechanisms and behaviour. The methods presented for interpreting the results using generic science demonstrate wider applications in both inhibited and non-inhibited environments. A review of inhibition in more extreme erosion-corrosion environments is performed to elucidate the effect of increased levels of erosion on the degradation process. The application of in-situ electrochemistry in dynamic conditions allowed the individual contribution of erosion and corrosion components of mass loss to be quantified, producing information on the different mechanisms by which inhibitors mitigate degradation effects. Finally, the optimum inhibitor in this study is broken down into is constituent components for individual analysis. A test matrix is implemented to determine the effect of synergy between the individual components. The adsorption process of the most influential component onto carbon steel is studied and determined through the implementation of electrochemistry and Fourier Transform Infrared Spectroscopy (FT-IR) before a colorimetric technique is tailored for residual analysis purposes.

The material documented in this thesis represents a contribution to the knowledge of the sponsoring company relating to assessment of the effects of two-phase flow on corrosion. Techniques available in the open literature for determining hydrodynamic characteristics of two-phase flow such as flow regimes and wall shear stresses were reviewed and compared with particular emphasis on stratified and slug flow regimes. The research work conducted improves the sponsoring company's knowledge and understanding of these areas providing a platform for undertaking two-phase flow related projects and developing / extending this business function. The work presented also enhances the company's qualitative understanding of momentum and mass transfer under two-phase flow providing a focus for driving future developments in laboratory based corrosion assessment. Initial work was undertaken to compare and validate hydrodynamic models studied using data available in the open literature a limited amount of which was from high pressure large diameter systems. This enhances confidence in models implemented and indicates the performance and accuracy expected. A feature of the work conducted of primary importance to the sponsoring company was generation of the first stages of a knowledge base supporting company projects whilst conforming to company QA procedures. In depth study of fundamental two-phase hydrodynamic models conducted during this research also provides a platform for future investment in commercially available technology. The material presented in this thesis enables investment in such technology with the benefit of detailed knowledge of models commonly used and critical understanding of expected performance and suitability.

When sand is present in carbon dioxide (CO2) corrosion environments in oil and gas pipe flow, wear rates of carbon steel pipelines can be severe. This wear mechanism is known as erosion-corrosion and consists of erosion and corrosion components, with degradation enhanced by interactions between the mechanisms. A lack of understanding of erosion-corrosion of carbon steel and the mechanisms contributing to enhanced degradation through erosion and corrosion interactions exists. Erosion-corrosion of carbon steel in CO2 conditions was the subject of investigation in this work. A submerged impinging jet (SIJ) was used to complete a case study of erosion-corrosion degradation of X65 carbon steel in field conditions at high flow velocities up to 20 m/s in a 60°C, pH 4.7, 2 wt.% NaCl solution containing up to 1000 mg/L of sand particles with an average diameter of 250 μm. High degradation rates, some in excess of 25 mm/yr, were measured and whilst corrosion inhibitors added to protect the X65 surface did reduce corrosion rates, they did not reduce erosion degradation, resulting in degradation rates remaining greater than 10 mm/yr in the most severe conditions evaluated. An investigation into the mechanisms of erosion-corrosion interactions revealed that work-hardened layers were thick and more refined on samples subject to erosion conditions compared with samples used in erosion-corrosion tests. This was explained by removal of the work-hardened layers, formed after particle impacts, through electrochemical dissolution, resulting in corrosion-enhanced erosion, which accounted for up to 20% of overall erosion-corrosion degradation at a flow velocity of 20 m/s in a 60°C, CO2-saturared solution containing 1000 mg/L of sand. Erosion-enhanced corrosion was shown not to be significant in the conditions tested. Flow geometry was also shown to have a significant influence on the erosion-corrosion degradation rates. A 90° elbow was designed to evaluate erosion-corrosion in pipe flow, CO2-saturated, pH 4 conditions at a flow velocity of 6 m/s that showed small erosion contributions to erosion-corrosion degradation on the outer radius of the elbow, with flow induced corrosion accounting for the majority of degradation. To fully understand erosion-corrosion conditions in both flow geometries, computational fluid dynamics (CFD) was used to predict mass transfer coefficients and sand particle trajectories in the flow. Predictions were used to define the erosion mechanisms in the different geometries and to explain why degradation rates could vary significantly between different flow geometries.

Aim: The prevalence of dental erosion is still increasing. A possible preventive approach might be rinsing with edible oils to improve the protective properties of the pellicle layer. This was tested in the present in situ study using safflower oil. Methods: Pellicle formation was carried out in situ on bovine enamel slabs fixed buccally to individual upper jaw splints (6 subjects). After 1 min of pellicle formation subjects rinsed with safflower oil for 10 min, subsequently the samples were exposed in the oral cavity for another 19 min. Enamel slabs without oral exposure and slabs exposed to the oral cavity for 30 min without any rinse served as controls. After pellicle formation in situ, slabs were incubated in HCl (pH 2; 2.3; 3) for 120 s, and kinetics of calcium and phosphate release were measured photometrically (arsenazo III, malachite green). Furthermore, the ultrastructure of the pellicles was evaluated by transmission electron microscopy (TEM). Results: Pellicle alone reduced erosive calcium and phosphate release significantly at all pH values. Pellicle modification by safflower oil resulted in an enhanced calcium loss at all pH values and caused an enhanced phosphate loss at pH 2.3. TEM indicated scattered accumulation of lipid micelles and irregular vesicle-like structures attached to the oil-treated pellicle layer. Acid etching affected the ultrastructure of the pellicle irrespective of oil rinsing. Conclusion: The protective properties of the pellicle layer against extensive erosive attacks are limited and mainly determined by pH. The protective effects are modified and reduced by rinses with safflower oil
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich

Aim: The prevalence of dental erosion is still increasing. A possible preventive approach might be rinsing with edible oils to improve the protective properties of the pellicle layer. This was tested in the present in situ study using safflower oil. Methods: Pellicle formation was carried out in situ on bovine enamel slabs fixed buccally to individual upper jaw splints (6 subjects). After 1 min of pellicle formation subjects rinsed with safflower oil for 10 min, subsequently the samples were exposed in the oral cavity for another 19 min. Enamel slabs without oral exposure and slabs exposed to the oral cavity for 30 min without any rinse served as controls. After pellicle formation in situ, slabs were incubated in HCl (pH 2; 2.3; 3) for 120 s, and kinetics of calcium and phosphate release were measured photometrically (arsenazo III, malachite green). Furthermore, the ultrastructure of the pellicles was evaluated by transmission electron microscopy (TEM). Results: Pellicle alone reduced erosive calcium and phosphate release significantly at all pH values. Pellicle modification by safflower oil resulted in an enhanced calcium loss at all pH values and caused an enhanced phosphate loss at pH 2.3. TEM indicated scattered accumulation of lipid micelles and irregular vesicle-like structures attached to the oil-treated pellicle layer. Acid etching affected the ultrastructure of the pellicle irrespective of oil rinsing. Conclusion: The protective properties of the pellicle layer against extensive erosive attacks are limited and mainly determined by pH. The protective effects are modified and reduced by rinses with safflower oil.
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Oil Jet Cavitation Peening in Air (OPA) is capable of inducing compressive residual stress in standard aerospace materials. This paper demonstrates the process capabilities of OPA on Al 2024-T3. Specifically, changes in the workpiece residual stress, microhardness, mass loss and surface roughness are investigated as a function of the control parameters for the system. Additionally, the paper identifies a method to monitor the process in situ through the use of high frequency acoustic emission sensors. The results indicate the OPA process is capable of generating residual stresses comparable to those of standard shot peening, up to 60% of the yield strength of the material, at similar depths, around 300 µm. Finally, the acoustic emission signal may be utilized to monitor the process, specifically in predicting the microhardness and mass loss of the system.

Erosion and corrosion of piping and 'equlpments continues to be a problem for the oil and gas sector. This primarily occurs where water and entrained sand are present in produced water. The pipelines used to transport these products are often subjected to multiphase flow regimes, which can result in severe degradation of the internal surfaces with the presence of solid particles and an oil phase in the flow system, and the erosion-corrosion mechanisms become more complicated when compared with those seen in single-phase systems. Therefore, it is essential to understand the degradation mechanisms involved to enable effective material selection to be achieved. In this project, a study on sand mobility was conducted, which focused on the effect of the corrosion inhibitor and oil phase adsorption on the sand particles and the effect of the mobility of sand particles in a flow system. A flow loop coupled with a high-speed camera was designed to enable the sand transport to be visualised. With such a system, the consequence of the corrosion inhibitor and hydrocarbon phase, ISOPAR M, on the adsorption process of the sand particles, and the effect of adsorption on reducing the kinetic energy of sand particles were studied. Zeta potential, which is a function of the mobility of an electrical charge at the slip plane beyond which the electrical charges form a stable entity with the solid particle, was also introduced in this work to confirm the result of the sand transport and to define the condition at which adsorption is possible. The results of zeta potential were in good agreement with the results of the sand mobility obtained by the designed flow loop and adjusted jet impingement rig. The results showed that the adsorption of corrosion inhibitor on the surface of sand particles is only possible if the corrosion inhibitor acquires an opposite charge to the sand particles dispersed in solution (the attraction force is dominant). In the study, the erosion-corrosion of a carbon steel (API-5L-X65), 13Cr martensitic stainless steel and duplex/superduplex stainless steel (22Cr and 25Cr) were assessed by jet impingement using a combination of electrochemical tests and metal loss analysis. The assessments were conducted under a simulated CO2 erosive-corrosive oil and gas surface pipeline with the presence of hydrocarbon and corrosion inhibitor to understand the material degradation mechanisms under different testing media to enable supportive information to be provided for the mitigation of erosion-corrosion in the oil and gas industry. In-situ electrochemistry, LPR, was conducted in order to assess the contribution of the corrosion process on the total degradation of materials. Despite the significant effect of the solution containing 5 vol% ISOPAR M on the total weight loss (TWL), the addition of 5% ISOPAR M did not show a clear reduction in the corrosion rate (higher slope of I'1E/l'1i plot). It was proved in this project that the presence of 5 vol% ISOPAR M not only has an important role in reducing the impact velocity of sand particles, but using CFD simulation it was also proved that the particles had a lower impact angle, and, hence, reduced the overall damage to the mechanical component (erosion-corrosion). The other interesting feature identified in this study is the interaction between the corrosion inhibitor and oil phase, which resulted in enhancing the stability of the emulsion flow and the change in the wettability of the metal surface. Unlike other testing media, the measured contact angles of water droplets on API-5L-X65 surfaces, pre-exposed to the solution containing 100 ppm of corrosion inhibitor and 5 vol% hydrocarbon, led some sites on the surface to change to an oil wet, hydrophobic surface, thereby increasing the corrosion resistance. A three-level experimental design with full replication was developed for the purpose of developing a statistical model (using the commercial package Minitab™) relating to the total weight loss of API-5L-X65. Such a model will enhance the understanding of the performance of a material in a multiphase flow environment. This methodology allows the interaction between the most significant parameters on erosion corrosion to be studied. Finally, this thesis has added to the understanding of erosion-corrosion in conditions containing a hydrocarbon phase and sand particles.

Over fifty small sinkholes (~1 meter in depth and width) were found in conjunction with structural damage to homes in an area south of Cleveland, TX. The local geology lacks carbonate and evaporite deposits associated with normal sinkhole development through dissolution. The morphology and distribution of sinkholes, and the geologic setting of the site are consistent with piping erosion. However, the site lacked the significant hydraulic gradient or exit points for sediment associated with traditional piping erosion. In areas of sinkholes, geophysical measurements of apparent electrical conductivity delineated anomalously high conductivity levels that are interpreted as a brine release from a nearby oil-field waste injection well. The contaminated areas have sodium adsorption ratios (SAR) as high as 19, compared to background levels of 3. Sodium has been shown to cause dispersion of soil colloids, allowing for sediment transport at very low velocities. Thus, subsurface erosion of dispersed sediment could be possible without significant hydraulic gradients. This hypothesis is backed by the observation of the depletion of colloidal particles within the E-horizon of sinkholes. However, there is a lack of precedence of waste brines initiating colloid dispersion. Also, sodium dispersion is not thought to be an important process in piping erosion in humid settings such as this one. Therefore, laboratory experiments on samples from the site area, designed to simulate field conditions, were conducted to measure dispersion verses pH, SAR and electrical conductivity (EC). Analysis of the experimental data with neural networks showed that an increase in SAR did increase dispersion. A dispersion prediction map, constructed with the trained neural network and calibrated geophysical data, showed correlation between sinkhole locations and increased predicted dispersion. This research indicates that a contaminant high in sodium content has caused colloidal dispersion, which may have allowed nontraditional subsurface erosion to occur in an area lacking a significant hydraulic gradient.

Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, March 2005.
Thesis Advisor(s): Raymond Shreeve, Garth Hobson. Includes bibliographical references (p. 91-93). Also available online.

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CAPES
Nas diversas etapas processuais da indústria de petróleo – extração, recuperação, armazenamento, transporte e refino, os materiais metálicos são expostos a fluidos corrosivos e solicitações mecânicas. Na etapa de armazenamento, em tanques de petróleo, é possível evidenciar a presença de duas fases, uma oleosa e outra aquosa, que de forma isolada ou associada podem influenciar no processo corrosivo. No transporte de petróleo, apresenta-se o efeito de corrosão-erosão (C-E) gerado pela presença de sais, gases e partículas sólidas que prejudicam a integridade dos equipamentos. Este trabalho teve como objetivo avaliar o comportamento do aço ASTM 572 Gr50 exposto a óleo cru, água do mar e misturas desses fluidos em diferentes proporções; sob condições estáticas simulando tanques de armazenamento e dinâmicas, visando simular transporte dos fluidos. Foram realizados testes de imersão do aço em diferentes fluidos corrosivos (óleo cru, água do mar, misturas de óleo e água do mar nas proporções de 20 e 50 % em volume de água do mar), ao longo de 60 dias em condições estáticas e dinâmicas. O processo corrosivo do material exposto aos diferentes meios foi analisado através de ensaios de perda de massa, análises eletroquímicas de potencial de circuito aberto (PCA), polarização potenciodinâmica e espectroscopia de impedância eletroquímica (EIE). A morfologia da corrosão foi avaliada através de microscopia eletrônica de microscopia óptica (MO) e varredura (MEV). Testes de microdureza Vickers e análises microestruturais foram realizados para analisar a ocorrência de mudanças nas propriedades mecânicas dos aços. Os resultados evidenciaram a influência do teor de água do mar no processo corrosivo, onde foram observados maiores valores de taxa de corrosão para os sistemas contendo maior proporção de água do mar. O mecanismo de C-E, observado nos sistemas dinâmicos mostrou ser mais agressivo que o processo de corrosão isoladamente (sistemas estáticos) o que foi observado por meio dos maiores valores de taxa de corrosão e também pelas morfologias de processo de deterioração da superfície vista por MO e MEV, onde cavidades de maior longitude e pites internos foram observados para os sistema sujeitos ao processo de C-E. Não foram observadas mudanças significativas na microestrutura do material após exposição às condições de fluido estudadas. Os resultados de MEV mostraram a presença de corrosão localizada em todos os sistemas, inclusive para os sistemas contendo apenas óleo cru, que apresentou baixa taxa de corrosão. Os ensaios eletroquímicos de PCA, polarização e EIE realizados com os eletrólitos advindos dos ensaios de imersão (fase aquosa) mostraram que o contato entre fluidos distintos (óleo e água do mar) sob condições de agitação, promove uma intensa troca composicional entre os meios, aumentando a agressividade e modificando a interação metal/meio. O eletrólito proveniente do sistema dinâmico contendo mistura de óleo e água do mar (50%) foi o que se mostrou mais agressivo, visto que no ensaio de polarização linear apresentou o maior valor de densidade de corrente anódica.
In the various procedural stages of the oil industry - extraction, recovery, storage, transportation and refining, metal materials are exposed to corrosive fluids and mechanical stresses. In oil tanks of the storage step, it is possible to demonstrate the presence of two phases, an oily and other aqueous, which isolated or associated, can influence the corrosion process. In the oil transport the corrosion-erosion (C-E) effect is present and it is generated by the presence of salts, gases and solid particles that can influence the integrity of the equipment. This study aimed to evaluate the behavior of ASTM 572 GR50 steel exposed to crude oil, sea water and mixtures of these fluids in different proportions; under static conditions simulating storage tanks and dynamic conditions, aiming to simulate fluid transport. Immersion tests were performed in different corrosive fluids (crude oil, seawater, oil mixtures and sea water in the proportions of 20 to 50% by seawater volume) for 60 days, under static conditions and dynamics. The corrosive process of material exposed to different media was analyzed by mass loss tests and electrochemical analysis of open circuit potential (OCP), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The morphology of corrosion was assessed by microscopy optical (OM) and scanning electron microscopy (SEM). Vickers microhardness testing and microstructure analysis were performed to examine the changes occurring in the mechanical properties of steels. The results showed the influence of the seawater content in the corrosion process, in which were observed higher corrosion rate values for the systems containing higher proportion of seawater. The C-E mechanism, seen in dynamical systems proved to be more aggressive than corrosion process isolated (static systems) which was observed by means of higher corrosion rate values and also by the morphologies of the surface deterioration process seen by OM and SEM, where the greater length and internal cavities pits were observed for the system subject to the C-E process; There were not significant changes in the microstructure of the material after exposure to conditions fluid studied. SEM results showed the presence of localized corrosion on all systems, including systems containing only crude oil, which showed low corrosion rate. Electrochemical test OCP, polarization and EIS conducted with electrolytes arising from immersion tests (aqueous phase), showed that the contact between different fluids (oil and seawater) under agitation conditions, promotes an intense exchange compositional between the fluids, increasing the aggressiveness and modifying the metal/media interaction. The electrolyte from the dynamic system containing a mixture of oil and seawater (50%) was the more aggressive electrolyte, as can be seen in the linear polarization that showed the highest value of anodic current density.

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Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico
The study area consist in high sensitivity environments located on the northern coast of Rio Grande do Norte, Northeast Brazil. The barrier island are the main geomorphological features on the coastal landscape, being naturally instable and surrounded by industrial activities like oil fields, salt industry, shrimp farms and urban areas sometimes installed parallel to the coast, combined with coast engineering interventions. High energy hydrodynamic process are responsible for the morphological instability of the coast. The study was based on remote sensing data obtained between 1954 and 2007 which consist in orbital images from Landsat, CBERS and Ikonos satellites and aerial photos. With all data integrated on GIS environment it was possible to update thematic maps of geology, geomorphology, vegetation, soil and landuse and development of multitemporal maps pointing areas with erosion and depositions of sediments, defining the critical erosion process on this region. The bigger morphological changes are related to changes on wind patterns during the year, terrestrial and sea breezes during the day, with spits and barrier island migration, opening and closing of channels like the one parallel to the coast on the area of Serra and Macau oil fields. These factors combined with the significant reduction on sediment budgets due to the loss of natural spaces to sediment reworking contribute to the low resilience which tends to be growing on the area of Serra and Macau oil fields. In front of such scenery a detailed monitoring was done in order to find technological possibilities for coastal restoration. A pilot area was defined to start the project of mangrove restore together with beach nourishment in order to minimize the effect of the erosion caused by the channel parallel to the coast, contributing to stabilize the northeast channel as the main one. It s expected that such methodology will aid the coastal environments restoration and the balance between industrial activities and coastal erosion
A ?rea de estudo est? inserida no litoral setentrional do Rio Grande do Norte, situado no extremo NE do Brasil, apresenta ambientes de alta sensibilidade ambiental tendo como principal caracter?stica na geomorfologia do litoral as ilhas barreiras, ambientes fr?geis e ef?meros circundado por atividades antr?picas como os campos petrol?feros, a atividade salineira, de carcinicultura e ?reas urbanas. A regi?o ? caracterizada por processos hidrodin?micos de alta energia respons?veis pela intensa a??o da din?mica costeira. O estudo foi realizado tendo como base dados entre 1954 e 2007 obtidos com o uso de sensores orbitais ?pticos: Landsat, CBERS, Ikonos e fotografias a?reas, validadas por fotografias a?reas de pequeno formato adquiridas ao longo dos anos. Com todos os dados integrados em ambiente SIG, foi atualizado o mapa Geol?gico, Geomorfol?gico, Vegeta??o, Pedol?gico, de Uso e Ocupa??o do Solo do BDAG e confeccionado os mapas multitemporais, apontando como resultado o mapeamento das ?reas de acres??o e de eros?o de sedimentos, caracterizando o processo de eros?o como cr?tico na ?rea do estudo. As altera??es morfol?gicas de maior magnitude observadas est?o relacionadas ? modifica??o no padr?o anual de ventos, destacando-se as brisas marinhas e terrestres na circula??o di?ria, com migra??o dos spits e das ilhas barreiras dominadas por mar?, levando a abertura e fechamento de canais de mar?, em especial do canal paralelo ? linha de costa, pr?ximo aos campos petrol?feros, proporciona uma redu??o significativa de aporte de sedimento na zona costeira, devido ? indisponibilidade de espa?o natural para o retrabalhamento do sedimento. Estes fatores combinados contribuem para a baixa resili?ncia1 que tende a ser crescente na ?rea dos Campos de Serra e Macau. Dentro deste cen?rio, foi realizado um levantamento minucioso buscando alternativas tecnol?gicas de restaura??o costeira. Enfim, por se tratar de ambientes predominantemente de ilhas barreiras, foi mapeada uma ?rea piloto, onde ? sugerida a instala??o do projeto de restaura??o dos ecossistemas de manguezais, combinada com restaura??o ecol?gica de engordamento de praia, buscando minimizar o efeito do Canal paralelo ? linha de costa, corroborando para a estabiliza??o do canal noroeste como o canal preferencial. Espera-se com esta estrat?gia metodol?gica contribuir para a restaura??o de ambientes costeiros e o conv?vio da atividade com a problem?tica da eros?o costeira

A partir d’une approche pluridisciplinaire (géo-historique, cartographique et pédologique), cette étude nous a permis d’établir un bilan complet sur l’état (origines, formes et évolutions) des systèmes de haies en Alsace depuis le Moyen Age. L’étude pédologique de topo séquences de sols dans des zones de loess très sensibles à l’érosion (Habsheim, Uffheim) a également permis de procéder à un bilan de l’érosion depuis le Néolithique et montré comment le stockage de colluvions à l’amont de haies modifiait le relief par la formation de rideaux de culture, dont les plus anciens remontent à la fin de l’Age du bronze. Nous avons quantifié le potentiel des systèmes de haies en tant que frein à l’érosion et en tant que puits de carbone, dans l’optique d’une lutte contre le réchauffement climatique (initiative 4‰). En termes de potentiel de stockage de colluvions, le site d’Habsheim révèle une capacité de stockage énorme avec par exemple des stockages de 17,8 t/m linéaire de haie. D’autre part, à partir de nos sites de référence, on a pu démontrer aussi la grande activité érosive de ces espaces et cela depuis la préhistoire : entre 5700 et 2700 BP le taux d’érosion moyen mesuré a été de 4,5 t/ha/an, équivalant à celui de l’agriculture intensive dans les mêmes zones, ce qui relativise en partie le rôle de l’agriculture moderne. Le potentiel réel des colluvions loessiques est plus nuancé en termes de stockage de carbone. De nombreux processus comme la minéralisation du carbone et la faible efficacité du complexe argilohumique rendent les interprétations délicates sans pour autant que le potentiel des sols agricoles limoneux comme puit de carbone doive être écarté
This study is a pluridisciplinary approach combining geohistory, spatial study and soil science that proposes an exhaustive analysis of origins, shapes and evolution of hedges systems in Alsace since Middle Ages. An erosion budget since Neolithic was obtained from the study of soil topographical sequences in an erosion sensitive loess area (Habsheim, Uffheim, 68, France). The colluvium stored in the upperside of the hedge modifies the topography by creating lynchets (the oldest were from the Bronze Age). We quantified the potential of hedges systems to reduce erosion and to store carbon in order to struggle against climate change (4‰ project). In Habsheim the storage of carbon potential is huge with some stocks reaching 17,8 t per meter of linear hedge. Moreover, based on the reference sites, we demonstrated the great erosion processes that has occured in these landscapes since Prehistory: between 5700 and 2700 BP the average erosion rate measured (4,5 t/ha/yr) is equivalent to the present day rates under intensive agriculture. The potential of loess colluvium, from the stock of carbon point of view, is more questionable. Interpretations are more difficult because of processes like mineralization of carbon and low efficiency of argilo-humic complex but so far the storage function of loamy soils cannot be neglected

Maintaining future agricultural productivity and ensuring soil security is of global concern and requires evidence-based management practices. Moreover, understanding where and when land is at risk of erosion is a fundamental step to combatting future soil loss and reach Land Degradation Neutrality (LDN). However, this is a difficult task because of the high spatial and temporal variability of the controlling factors involved. Therefore, tools investigating the impact and frequency of extreme erosive events are crucial for land managers and policymakers to apply corrective measures for better erosion management in the future. While the utility of using wind and water erosion models for management is well established, there is a paucity of work on the impact of climate change and extreme environmental conditions (e.g. wildfires) on soil erosion by wind and water simultaneously. Both erosion types are controlled by different environmental variable that vary highly in space and time. Therefore, the overarching aim of this study was to develop a joint wind-water erosion modelling method and demonstrate the utility of this approach to identify (1) the spatio-temporal variability of extreme erosion events in the South Australian agricultural zone (Australia) and (2) assess the likely increase of this variability in the face of climate change and the recurrence of wildfires. To fulfil the aim of the research project, we adapted two state-of-the-art wind and water (hillslope) erosion models to integrate modern high-resolution datasets for spatial and temporal analysis of erosion. The adaptation of these models to local conditions and the use of high-resolution datasets was essential to ensure reliable erosion assessment. First, we applied these models separately in the Eyre Peninsula and Mid-North agricultural regions. We evaluated the spatio-temporal variability of extreme erosion events between 2001 and 2017 and described the complex interactions between each erosional process and their influencing factors (e.g. soil types, climate conditions, and vegetation cover). Hillslope erosion was very low for most of the Eyre Peninsula; however, a large proportion of the central Mid-North region frequently recorded severe erosion (> 0.022 t ha-1) two to three months per year, for most of the years in the time-series. The most severe erosion events were primarily driven by topography, low ground cover (< 50%) and extreme rainfall erosivity (> 500 MJ mm ha-1 h-1). Average annual wind erosion was very low and comparable in the two regions. Nonetheless, most of the west coast of the Eyre Peninsula frequently registered severe erosion (> 0.000945 t ha-1 or 0.945 kg ha-1) two to three months per year, for most of the years. The most severe erosion events were largely driven by the soil type (sandy soils), recurring low ground cover (< 50 %) and extreme wind gusts (> 68 km h-1). We identified that erosion severity was low for the vast majority of the study area, while 4% and 9% of the total area suffered severe erosion by water and wind respectively, demonstrating an extreme spatial and temporal skewness of soil erosion processes. Then we combined the modelling outputs from the wind and water erosion models and tested the models’ response to major wildfire events. This research demonstrated how erosion modelling could be used to predict the impact of severe wildfire events on soil erosion. The two models satisfactorily captured the spatial and temporal variability of post-fire erosion. However, a very small fraction of the region (0.7%) was severely impacted by both wind and water erosion. We observed that soil erosion increased immediately after the wildfires or within the first six months for the ten fire-affected regions. For three of the wildfire events, the models showed an increase in wind and water erosion in consecutive months or at the same time. These results highlighted the importance to consider wind and water erosion simultaneously for post-fire erosion assessment in dryland agricultural regions. Finally, we had the rare opportunity to assess the impact of a catastrophic wildfire event on wind erosion in an agricultural landscape by examining the influence of unburnt stubble patches on adjacent burnt or bare plots using a spatio-temporal sampling design. The field study allowed a quantitative assessment of spatial and temporal patterns of wind erosion and sediment transport after a catastrophic wildfire event. It showed very high levels of spatial variability of erosion processes between burnt and bare patches and demonstrated how measuring field-scale sediment transport could complement fine-scale experimental studies to assess environmental processes at the field scale. This research highlights the utility of erosion models to inform corrective measures for future land management. We have implemented tools that allow a realistic assessment of the influence of climate change and extreme environmental conditions scenarios on soil erosion for a wide range of land cover over large regions. Here, the models enabled the identification of the relative post-fire wind or water erosion risk in dryland agricultural landscapes, making them particularly useful for land management under future uncertainty. Spatial patterns compared well with previous modelling approaches and underpinned the benefit of erosion models to assess spatial differences in erosion risk and evaluate corrective measures at the regional scale. However, modelled soil erosion magnitudes strongly depend on how the influence of soils is implemented in the models, making it difficult to set absolute quantitative soil loss targets for land management. The thesis has provided a proof of concept of the approach for South Australia. However, all input data can be freely sourced Australia-wide and similar dataset are available globally.
Thesis (Ph.D.) -- University of Adelaide, School of Biological Sciences, 2020

The Electrical Submersible Pump (ESP) manufactured by Baker Hughes, model no. WJE-1000 is designed for wells that are expected to have a high content of abrasive solids. It is a mixed flow, tandem compression type pump. Although the erosion of the pump diffuser and impeller stages are significant, the ESP study shows that the most sever failure is due to components that affect the pump’s rotor dynamics such as radial bearings and impeller seals when eroded with 100 mesh sand. Erosion of these seals will result in an internal leakage that can significantly affect stage pressure rise, efficiency, power consumption, vibration, pump life and running cost. The erosion study utilizing 100 mesh fracture sand at 0.2% concentration, with the pump operating at 3600 RPM, 40 PSI intake pressure, 1150 GPM for over 117 hours comparisons are made to the pump’s baseline performance. Measurements of the rotor bearings, impeller seals and their corresponding stators showed that the wear patterns generally increase with time and differ by location. Stage 1 bearings and seals suffered the least amount of erosion and stage 3 rotor components suffered the most erosion. The maximum change in stage 3 bearing clearances was 223% and the maximum change in stage 3 impeller seal clearances was 300%. Performance wise the total pump efficiency dropped by 6.77%, the total pressure rise dropped by 6.3%, the pump’s best efficiency point decreased by 0.78%, and the power consumption increased by 0.49%. Pump vibration patterns also changed with time and by location. The maximum shaft orbit diameter was at stage 3 and it grew 643% in diameter after 117 hours of erosion. The waterfall plots of the pump’s ramp up changed significantly with time. After 117 hours at 3600 RPM, sub-synchronous oscillations at 67% of the synchronous speed dominated the amplitude peaks showing that the rotor vibration locked with the rotor’s first natural frequency at around 2500 RPM. After 117 hours, another sub-synchronous started showing a peak at the rotor’s second natural frequency at 1500 RPM.

Understanding how swirl flows can be applied to processes in the oil and gas industry and how problems might hinder them, are the focus of this thesis. Three application areas were identified: wet gas metering, liquid loading in gas wells and erosion at pipe bends due to sand transport. For all three areas, Computational Fluid Dynamics (CFD) simulations were performed. Where available, experimental data were used to validate the CFD results. As a part of this project, a new test loop was conceived for the investigation of sand erosion in pipes. The results obtained from CFD simulations of two-phase (air-water) flow through a pipe with a swirl-inducing device show that generating swirl flow leads to separation of the phases and creates distinct flow patterns within the pipe. This effect can be used in each of the three application areas of interest. For the wet gas metering application, a chart was generated, which suggests the location of maximum liquid deposition downstream of the swirling device used in the ANUMET meter. This will allow taking pressure and phase fraction measurements (from which the liquid flow rate can be determined) where they are most representative of the flow pattern assumed for the ANUMET calculation algorithms. For the liquid loading application, which was taken as an upscaling of the dimensions investigated for the wet gas metering application, the main focus was on the liquid hold-up. This parameter is defined as the ratio of the flowing area occupied by liquid to the total area. Results obtained with CFD simulations showed that as the water rate increases, the liquid hold-up increases, implying a more effective liquid removal. Thus, it was concluded that the introduction of a swirler can help unload liquid from a gas well, although no investigation was carried out on the persistance of the swirl motion downstream of the device. For the third and final application, the erosion at pipe bends due to sand transport, the main focus was to check the erosion rate on the pipe wall with and without the introduction of a swirler. The erosion rate was predicted by CFD simulations. The flow that was investigated consisted of a liquid phase with solid particles suspended in it. The CFD results showed a significant reduction in erosion rate at the pipe walls when the swirler was introduced, which could translate into an extended working life for the pipe. An extensive literature review performed on this topic, complemented by the CFD simulations, showed the need for a dedicated multiphase test loop for the investigation of sand erosion in horizontal pipes and at bends. The design of a facility of this type is included in this thesis. The results obtained with this work are very encouraging and provide a broad perspective of applications of swirl flows and CFD for the oil and gas industry.

The discipline of Sociology has been quiet regarding the production of food by industrial agriculture. However, there are issues that potentially undermine the ability of industrial agriculture to continue to produce food at the same rate. These issues include: global climate change, aquifer depletion, soil erosion and exhaustion, the increase in global production of meat, the ever expanding global population and peak oil. This thesis considers how these issues will affect Manitoba’s agriculture, Manitoba’s ability to adapt to a period of change and its ability to continue to feed its population. Unstructured interviews with expert informants allowed for the collection of data that are not readily available. These data are combined with pre-existing data to assemble an agricultural profile. There are two competing theories within the current dialogue: limits-to-growth and ecological modernization. Ultimately, the food procurement practices will be assessed with reference to the limits-to-growth theory and recommendations will be made.

The Athabasca oil sands deposits in northern Alberta, Canada, are a naturally occurring mixture of bitumen, sand, clay and other minerals. Bitumen, which is a heavy and extremely viscous oil, is mined and then subsequently refined to produce gasoline, diesel and other hydrocarbon-based products. Moreover, the naturally occurring Athabasca Oil sands deposits are a source of both physical and chemical stressors to local rivers that flow through the deposit. Physical stress to aquatic biota from natural bitumen results from hillslope erosion processes and slumping of material into the rivers, while chemical stress arises from bitumen-derived contaminants entering the waters. To fully understand the ecological and cumulative effects of oil sands mining activities on aquatic ecosystem water quality and associated biological structure and function, there is a need to evaluate the effects of naturally occurring bitumen in the aquatic environment. Within this, the main objective of this thesis was to evaluate the possible ecotoxicological effects associated with the slumping of river bank material (i.e., oil sands deposit that naturally enters the river systems through fluvial geomorphological processes). For that, a series of inter-related laboratory ecotoxicological assays were conducted using benthic and pelagic aquatic invertebrates exposed to oil sands material collected from four different sources in regional rivers. Organisms were sensitive to the presence of oil sands elutriates, especially to elutriates generated from bitumen material collected in the banks of the Steepbank and Ells river, with effects on the life traits of Daphnia magna, Physa acuta, Vibrio fischeri, and Dugesia tigrina. When bitumen is mixed with sediment, it was also toxic to Chironomus riparius, which responded negatively revealing to be sensitive to bitumen samples with more bitumen content in sediments with a decrease in their body size, a delay on the emergence time, reduced total emergence and a decrease in the weight of imagoes. On a more complex approach, bitumen negatively affected natural communities collected from Rio Mau (Portugal) by reducing the number of Ephemera sp. and Chironomus sp. that feed on fine sediment particles. The use of solid bitumen samples and elutriates from those samples, combined with a suite of representative species and different experiments provides a comprehensive and holistic approach to assess effects of oil sands materials arising from bank erosion-related processes, emphasising the need to discriminate natural processes from mining-related activities of surface and groundwater contamination in oil sands areas.
Os depósitos de oil sands (ou areias petrolíferas) do Atabasca, situados no Norte de Alberta, Canadá, são uma mistura natural de betume, areia, argila e outros minerais. O betume é um tipo de petróleo extremamente viscoso que é extraído e posteriormente tratado para produção de gasolina, gasóleo e outros produtos compostos por hidrocarbonetos. O depósito natural das oil sands do Atabasca é uma fonte de stressores químicos e físicos para os rios da região que desaguam/fluem sobre esses depósitos. O stress físico causado pelo betume nos organismos aquáticos é resultado dos processos de erosão das encostas dos rios, enquanto o stress químico é resultante dos contaminantes derivados do betume que são depositados nos rios através da sua erosão. Para entender os efeitos ecológicos induzidos pela pressão antropogénica da utilização do betume na exploração petrolífera, é necessário identificar e avaliar quais os efeitos adjacentes a uma contaminação natural, originada pela erosão natural do betume. Com isto, o objetivo principal desta tese consistiu em avaliar/analisar os possíveis efeitos ecotoxicológicos associados aos processos de erosão do betume nos rios. Para isso, foram realizados uma série de ensaios ecotoxicológicos, utilizando invertebrados aquáticos bentónicos e pelágicos expostos a betume recolhido das encostas de rios que correm sobre depósitos de betume. Esta exposição foi efetuada de forma direta, misturando o betume no sedimento ou através de elutriados obtidos deste betume. Verificou-se que estes organismos são sensíveis à presença de elutriados de betume recolhido nas encostas dos rios Steepbank e Ells, afetando diversos parâmetros vitais de espécies modelo como o pequeno crustáceo planctónico Daphnia magna, a bactéria Vibrio fischeri, o caracol de água doce Physa acuta e a planária Dugesia tigrina. Quando o betume foi incorporado no sedimento, induziu toxicidade na espécie Chironomus riparius, que respondeu negativamente à sua presença, revelando assim a sua sensibilidade ao betume. Verificaram-se reduções do seu tamanho larvar, aumento do seu tempo à emergência, redução da sua emergência total e uma diminuição de peso dos adultos. Utilizando uma abordagem mais complexa, um ensaio de mesocosmos foi efetuado com uma comunidade natural de invertebrados recolhida no Rio Mau (Portugal). A incorporação do betume no sedimento induziu efeitos negativos e maioritariamente observados na redução da abundância de Ephemera sp. e Chironomus sp que se alimentam essencialmente de partículas finas de sedimento onde o betume está incorporado, levando assim a efeitos tóxicos nos organismos. O uso de amostras de betume e respetivos elutriados, em combinação com o uso de uma série de organismos aquáticos utilizados em diferentes tipos de ensaios, forneceram uma abordagem mais realista e holística, na avaliação dos efeitos dos processos naturais que levam à entrada de betume em rios da área de estudo. Estes resultados enfatizam a necessidade de estudar mais aprofundadamente a influência da entrada do betume nos rios, diferenciando assim, os possíveis efeitos causados por processos naturais e os efeitos causados pela pressão antropogénica.
Programa Doutoral em Biologia

Objective: Toothbrushing with fluoride toothpaste followed by rinsing with mouthwash is a routine procedure to maintain good oral hygiene. It is unknown to what extent these rinses can modulate the effect of fluoride in its ability to prevent erosion/abrasion.The aim of this in-vitro study was to investigate and compare the impact of chlorhexidine (CHX), essential oils (EO) and cetylpyridinium chloride (CPC) mouthrinses on erosive tooth wear protection afforded by conventional fluoride toothpastes. Materials and Methods: The following experimental factors were considered: five rinses: CHX, EO, CPC, a fluoride rinse, and deionized water, two fluoride toothpastes: stannous fluoride (SnF2) or sodium fluoride (NaF) and two models: (erosion/ erosion+abrasion). Slabs of bovine enamel and dentin were prepared and embedded in resin blocks and generated 10 enamel and dentin testing groups (n = 8). UPVC tapes were placed on the sides of each slab leaving 1mm area exposed in the center. The blocks were subjected to a five-day cycling model. Then, the blocks were placed in a brushing machine and exposed to fluoride toothpaste slurry (one side was brushed and the other wasn’t). The blocks were then exposed to rinse treatments. Artificial saliva was used to remineralize the specimens after erosions and treatment challenges, and as storage media. After the fifth day of cycling, surface loss (in micrometers) was determined by profilometer. Data were analyzed using ANOVA (α = 0.05). Results: There was no interaction among the three factors (type of toothpaste, mouthrinse and abrasion or not (dentin p = 0.0520, enamel p = 0.4720). There were no significant two-way interactions as SL was only affected by toothpaste and mouthrinse. NaF caused less SL than SnF2 (4.60 vs. 5.83 μm; p < 0.0001) in dentin, whereas the opposite was found in enamel (5.20 vs. 3.56 μm; p < 0.0001). Toothbrushing abrasion caused comparatively more SL in enamel (6.53 vs. 2.23 μm; p < 0.0001) than in dentin (6.06 vs. 4.38 μm; p < 0.0001). None of the tested mouthrinses affected SL. Conclusion: Commonly used mouthrinses containing antimicrobial agents or additional fluoride, do not impair the erosion/abrasion protection afforded by fluoride toothpastes. Tested SnF2 dentifrice offered greater protection against enamel surface loss and NaF dentifrices showed more protection for the dentin surface. Clinical relevance: The understanding of the interaction between commonly used rinses and fluoride dentifrices will help dentists provide better recommendations to patients with erosive lesions.