Search

Summary Hydrate formation is an issue that can have a significant negative economic impact on the oil industry. Hydrates are crystalline solids that resemble ice, usually formed in the presence of a mixture of oil/gas/water in conditions of high pressure and low temperature, similar to those found in deepwater oil production. Depending on the amount of hydrates formed, production lines can be severely affected, causing huge financial losses. Therefore, it is of great interest to understand and analyze the characteristics of the hydrates formed, and eventually identify means of mitigating hydrate formation, to reduce the production losses. In this work we analyze the effect of alcohols for hydrate mitigation through rheological characterization. We study the rheology of hydrates formed in a mixture of tetrahydrofuran (THF) and water. This is used as a model system because hydrates are formed at atmospheric pressure. Using the rheology of the model system as a baseline case, we analyze the effect of different alcohols (monoethylene glycol, ethanol, isopropanol) and concentrations on the rheology of the resulting hydrate slurries to verify and understand the capability of these additives to mitigate hydrate formation.

Transient operations in oil and gas production can result in conditions with a high potential for the formation of hydrate plugs. In restart operations, the shear flow and the increased pressure ca...

The oil and gas production in deeper water scenarios (e.g. pre-salt) has been increasing due to the growth in industrial production. The exploration fields under more severe conditions is accompanied by concerns about solid precipitation/deposition and hydrate formation. Transient operations, involving shut-in and restart is the most challenging scenario with risk for hydrate problem. The residence time of the production fluids associated to the rate of heat loss to the ambient seabed during the period of shut-in may increase the potential risk of hydrate blockage. This work is focused on understanding the hydrate formation, breakup, agglomeration and deposition, reproducing the shut-in and restart conditions in a lab-scale. Experiments were performed using a high pressure cell coupled to a rheometer using a custom-designed impeller and a rocking cell experiments with visual capabilities. A two-phase (water and gas) and three-phase (water, oil and gas) systems were used in the experiments. Also, the impact of the shear applied at restart on the hydrate morphology was evaluated. The viscoelastic behavior was observed in most shut-in and restart tests. Understanding the mechanism of hydrate formation and agglomeration during transient conditions may help to develop strategies to avoid hydrate plugging and allow the formation of a hydrate slurry yielding flowable conditions.

In offshore oil production, scheduled or emergency shutdowns of the production system may occur due to maintenance, equipment failure, production issues, and weather-related events. During the shut-in, the fluids may enter into the hydrate zone because of the thermal energy transfer to the cold ocean waters, increasing the risk of hydrate formation during the shut-in period and upon the restart of the production system. This work is focused on identifying some parameters that influence the hydrate formation in shut-in and restart conditions. Using a rock-flow cell with visual capabilities, the hydrate formation and the phenomena involved upon the restart were investigated. The main results of the experiments showed that the high shear conditions applied at the restart promoted water dispersion into the oil phase and contributed to the dispersion of hydrates. In addition, the low shear rate favored the formation of hydrate deposits while hydrate agglomerate was formed at high shear rate. Besides the shear rate, the subcooling proved to be an important parameter that favors the hydrate formation under sheared conditions. Conditions with high subcooling and low water cut promoted the formation of small hydrate particles (~2 mm) that can be dispersed in the oil-phase even without the anti-agglomerant. A high subcooling promoted the formation of “dry” hydrates, preventing the particles to stick with each other (agglomerates). The results indicated that subcooling is an important parameter to ensure a safe restart in the pipeline. Lastly, the addition of an anti-agglomerant reduced the water–oil interfacial tension, which promoted the water/hydrate dispersion; the effectiveness of the anti-agglomerant was clearly affected by the shear and the water cut.

Introdução: Analisar a prevalência das anomalias congénitas, detetadas no nascimento, entre filhos de gestantes adolescentes, enfatizando os tipos mais comuns e a época do diagnóstico.Material e Métodos: Estudo retrospetivo do tipo censo, no qual foram analisados todos recém-nascidos, vivos ou mortos, com peso superior a 500 g, de mulheres que tiveram o parto no Hospital São Paulo num período de seis anos. Os produtos da conceção portadores de anomalias foram identificados no período pré-natal ou através do exame físico pós-natal, segundo os critérios do Estudo Colaborativo Latino-Americano das Malformações Congênitas. Os resultados são apresentados de forma descritiva através de valores absolutos e relativos, calcula-se a prevalência das anomalias e comparam-se os diferentes grupos recorrendo a testes não paramétricos.Resultados: Foram analisadas 6 257 gestações, das quais 577 resultaram em recém-nascidos com alguma anomalia congénita identificada no nascimento (prevalência de 9,2%). Do total de gestações, 907 eram de adolescentes (idade inferior a 20 anos), para as quais se verificou uma prevalência de anomalias nos recém-nascidos de 9,9%. Comparando os recém-nascidos de adolescentes com os das mulheres com idade superior a 20 anos, apenas se encontrou diferença estatisticamente significativa para a prevalência dos defeitos do tubo neural (p = 0,027).Discussão: Observamos uma alta taxa de partos em adolescentes, acima das taxas dos países desenvolvidos. Observamos também alta frequência de anomalias congénitas em recém-nascidos, provavelmente por sermos um serviço terciário de referência. A elevada prevalência dos defeitos do tubo neural entre grávidas jovens pode ser explicada pela não suplementação pré-concecional de ácido fólico em gravidezes não planeadas, como é característico nas adolescentes.Conclusão: A prevalência e momento do diagnóstico das anomalias congénitas em recém-nascidos apresentam comportamentos semelhantes entre grávidas com idade inferior ou superior a 20 anos, exceto para os defeitos do tubo neural, de maior prevalência nos recém-nascidos das grávidas adolescentes.

One of the main issues in the area of drilling and production in deep and ultra-deep water in the oil industry is the formation of natural gas hydrates. Hydrates are crystalline structures resembling ice, which are usually formed in conditions of high pressure and low temperature. Once these structures are formed, they can grow and agglomerate, forming plugs that can eventually completely or partially block the production lines, causing huge financial losses. To predict flow behavior of these fluids inside the production lines, it is necessary to understand their mechanical behavior. This work analyzes the rheological behavior of hydrates slurries formed by a mixture of water and Tetrahydrofuran (THF) under high pressure and low temperature conditions, close to the ones found in deep water oil exploration. The THF hydrates form similar structures as the hydrates originally formed in the water-in-oil emulsions in the presence of natural gas, at extreme conditions of high pressure and low temperature. The experiments revealed some important issues that need to be taken into account in the rheological measurements. The results obtained show that the hydrate slurry viscosity increases with pressure. Oscillatory tests showed that elasticity and yield stress also increase with pressure.

Advanced Oxidative Processes (AOP) have been successfully employed as efficient water treatment methods. The utilization of AOP on drinking and wastewater represents currently an alternative to costly, hazardous, and slow processes. In order to further establish the ground basis for AOP in water safety and security, reliable and consistent methods of analysis are required. As an alternative to basic statistical methods, which may not successfully describe and forecast the application of a given treatment methodology of water, the use of chemometrics has increased significantly over the past decades. Chemometric analyses are an intersection between analytical chemistry and applied statistical models in order to predict and extract information from a given condition. This chapter introduces the concepts of chemometrics in environmental engineering issues and the utilization of experimental design to efficiently analyze experimental data in environmental samples. Two case studies are presented to demonstrate the importance of chemometrics in water analyses: (1) considering a Taguchi L16 experimental design, and an optimization study using Response Surface Methodology, to evaluate photo-Fenton and ozone AOP-based treatment on an effluent with high concentration of organic matter; (2) using a Taguchi L9 array to evaluate the combination of photocatalytic degradation and AOP of an industrial effluent. The results showed in this chapter demonstrate how a given statistical method can be successfully employed within the intersection of environmental analyses and water issues.

To analyze the prevalence of congenital anomalies detected at birth among children of pregnant adolescents, emphasizing the most common types and the time of diagnosis.Retrospective study of type census, in which were analyzed in all newborns, living or dead, weighing more than 500 g of women who gave birth at Hospital São Paulo in a period of six years. The fetuses bearing anomalies were identified prenatally or through postnatal physical examination period, according to the criteria of the Latin American Collaborative Study of Congenital Malformations. The results were expressed descriptively using absolute and relative values, the prevalence of anomalies was calculated, as well as the comparison between groups using nonparametric tests.We analyzed 6 257 pregnancies, of which 577 newborns had some congenital anomaly identified at birth (prevalence 9.2%). Among these 6 257, 907 were adolescents, which showed a 9.9% prevalence of anomalies among their newborns. There was no significant difference between the presence of abnormalities in newborns of adolescents and women with age greater than or equal to 20 years. About 56% of congenital anomalies were diagnosed in the prenatal period. We observed a higher prevalence of defects of neural tube between newborns of adolescents (p = 0.027).We observed high rate of deliveries in adolescents, higher than developed countries. We observed also high frequency of congenital anomalies in newborns, probably because our tertiary reference center. The high prevalence of neural tube defect among young pregnant women could be explained by the absent of acid folic supplementation in non-planned gestations which is typical of adolescents.The prevalence and time of diagnosis of congenital anomalies showed similar behavior among newborns of teenagers and women with age greater than or equal to 20 years, except for the defects of the neural tube, which were more prevalent among newborns of teenagers.Introdução: Analisar a prevalência das anomalias congénitas, detetadas no nascimento, entre filhos de gestantes adolescentes, enfatizando os tipos mais comuns e a época do diagnóstico. Material e Métodos: Estudo retrospetivo do tipo censo, no qual foram analisados todos recém-nascidos, vivos ou mortos, com peso superior a 500 g, de mulheres que tiveram o parto no Hospital São Paulo num período de seis anos. Os produtos da conceção portadores de anomalias foram identificados no período pré-natal ou através do exame físico pós-natal, segundo os critérios do Estudo Colaborativo Latino-Americano das Malformações Congênitas. Os resultados são apresentados de forma descritiva através de valores absolutos e relativos, calcula-se a prevalência das anomalias e comparam-se os diferentes grupos recorrendo a testes não paramétricos. Resultados: Foram analisadas 6 257 gestações, das quais 577 resultaram em recém-nascidos com alguma anomalia congénita identificada no nascimento (prevalência de 9,2%). Do total de gestações, 907 eram de adolescentes (idade inferior a 20 anos), para as quais se verificou uma prevalência de anomalias nos recém-nascidos de 9,9%. Comparando os recém-nascidos de adolescentes com os das mulheres com idade superior a 20 anos, apenas se encontrou diferença estatisticamente significativa para a prevalência dos defeitos do tubo neural (p = 0,027). Discussão: Observamos uma alta taxa de partos em adolescentes, acima das taxas dos países desenvolvidos. Observamos também alta frequência de anomalias congénitas em recém-nascidos, provavelmente por sermos um serviço terciário de referência. A elevada prevalência dos defeitos do tubo neural entre grávidas jovens pode ser explicada pela não suplementação pré-concecional de ácido fólico em gravidezes não planeadas, como é característico nas adolescentes.Conclusão: A prevalência e momento do diagnóstico das anomalias congénitas em recém-nascidos apresentam comportamentos semelhantes entre grávidas com idade inferior ou superior a 20 anos, exceto para os defeitos do tubo neural, de maior prevalência nos recém-nascidos das grávidas adolescentes.

Over the last decades, environmental concerns have become more critical and frequent. Thisis, mainly, due to population growth and the increase of industrial activities in which anthro‐pogenic actions have reached catastrophic proportions resulting in changes of soil, air, andwater quality [1].Environmental pollution by industrial effluent is being characterized as one of the major causesof the aggravation of this problem. Residues, in general, produce diversified compounds,containing, frequently, pollutants that are toxic and resistant to conventional treatments suchas coagulation/flocculation or biodegradation [2], and they are eventually discharged, in mostof the cases, in an inadequate way causing severe damages. Regarding the environmentalproblem, researchers were driven to study the feasibility of new techniques and methodolo‐gies, as well as, the emission and pollutant discharge control. In order to apply the pollutioncontrol and to attend environmental legislation, patterns and quality indicators were estab‐lished. In terms of water quality: oxygen concentration, phenols, Hg, pH, temperature, amongother requirements [3].Companies search for new environmental alternatives to treat generated residuals. Theenvironmental reality is demanding for further actions to mitigate industrial impacts on water.Therefore, water treatment has become a mandatory investment to industries, institutions, andothers with the aim to attending environmental laws, as well as ISO 14000 series.

Industrial processes can create a wide variety of chemicals that pollute the air and water, with adverse impacts to ecosystems and humans. These impacts are caused by the polluting compounds that have toxic, carcinogenic, and also mutagenic properties (Busca et al., 2008). The treatment of wastewater containing phenolic compounds can be accomplished using applied principles of chemical oxidation, settling, membrane filtration, osmosis, ion, precipitation, and coagulation among other methods (Lin; Juang, 2009).

Taguchi’s L16 orthogonal array in the study of removal of total phenols using advanced oxidation processes was efficient. In the statistical assessment, the input variables obtained as significant through ANOVA were: hydrogen peroxide (F = 10.0924 and p-value = 5.02) and ozone (F = 3.8686 and p-value = 14.39). In this assessment, the best experimental condition for the removal of total phenols is 100%. The following factors must therefore be adjusted: hydrogen peroxide = 38, 7g and ozone flow = 3 L/h.