Elemental sulphur (S⁰) is removed from sour gas deposits (high H₂S) during refinement. The resulting S⁰ is often stored onsite when the costs of shipping S⁰ to market exceeds the costs of storing it in large above ground blocks. With the aid of acidiphilic bacteria, atmospheric air and water oxidize S⁰ to sulphate (SO₄^2-). Long term storage is under consideration; however, oxidation rates and the role of each oxygen source (O_2(g) and H₂O) is not clear. S⁰ oxidation experiments were conducted over a range of temperatures (6-32¡ãC) to investigate reaction rates and isotopic fractionation of O and S isotopes during oxidation. The experiments also investigated the effect of integrating S⁰ oxidizing microorganisms and available nutrients on both the reaction rates and isotope fractionation. Results indicated > 95% of total SO₄^2- generated can be attributed to autotrophic microbial activity. Experiments conducted in a nutrient rich mineral solution showed rates increase with temperature from 0.16 (6¡ãC) to 0.98 (32¡ãC) ¦Ìg S⁰ cm^-2 d^-1 (Q₁₀ ¡Ö 1.7 - 1.9). Experiments conducted in a nutrient poor solution (deionized water) showed oxidation rates did not increase with temperature (0.06 to 0.08 ¦Ìg S⁰ cm^-2 d^-1) between 12 and 32¡ãC. Oxygen isotope analysis of the generated SO₄^2- indicated essentially all oxygen incorporated into the SO₄^2- originated from H₂O. In addition, effluent samples obtained from S⁰ block effluent at SCL indicated ¦Ä¹⁸O_(SO4) generally reflected the ¦Ä¹⁸O_(H2O) in the system at the time of oxidation. While covering the S⁰ blocks with an impermeable cover would undoubtedly minimize total SO₄^2- accumulation in block effluent, the results of this study suggest ¦Ä¹⁸O_(SO4) can also be used to track water movement through the block.

Elemental sulphur (S⁰) is removed from sour gas deposits (high H₂S) during refinement. The resulting S⁰ is often stored onsite when the costs of shipping S⁰ to market exceeds the costs of storing it in large above ground blocks. With the aid of acidiphilic bacteria, atmospheric air and water oxidize S⁰ to sulphate (SO₄^2-). Long term storage is under consideration; however, oxidation rates and the role of each oxygen source (O_2(g) and H₂O) is not clear. S⁰ oxidation experiments were conducted over a range of temperatures (6-32¡ãC) to investigate reaction rates and isotopic fractionation of O and S isotopes during oxidation. The experiments also investigated the effect of integrating S⁰ oxidizing microorganisms and available nutrients on both the reaction rates and isotope fractionation. Results indicated > 95% of total SO₄^2- generated can be attributed to autotrophic microbial activity. Experiments conducted in a nutrient rich mineral solution showed rates increase with temperature from 0.16 (6¡ãC) to 0.98 (32¡ãC) ¦Ìg S⁰ cm^-2 d^-1 (Q₁₀ ¡Ö 1.7 - 1.9). Experiments conducted in a nutrient poor solution (deionized water) showed oxidation rates did not increase with temperature (0.06 to 0.08 ¦Ìg S⁰ cm^-2 d^-1) between 12 and 32¡ãC. Oxygen isotope analysis of the generated SO₄^2- indicated essentially all oxygen incorporated into the SO₄^2- originated from H₂O. In addition, effluent samples obtained from S⁰ block effluent at SCL indicated ¦Ä¹⁸O_(SO4) generally reflected the ¦Ä¹⁸O_(H2O) in the system at the time of oxidation. While covering the S⁰ blocks with an impermeable cover would undoubtedly minimize total SO₄^2- accumulation in block effluent, the results of this study suggest ¦Ä¹⁸O_(SO4) can also be used to track water movement through the block.

The glassy copolyimide 6FDA-DAM:DABA was investigated as a polymer backbone for membranes used in aggressive sour gas separation applications. An esterification crosslinking mechanism enabled the synthesis of materials with augmented H₂S/CH₄ selectivity and plasticization resistance. These materials make use of polyethylene glycol (PEG) crosslinking agents and are referred to as PEGMC polymers. Rigorous dense film characterization of the novel crosslinkable materials indicates that excellent H₂S/CH₄ selectivity (24) is achievable while still maintaining high CO₂/CH₄ selectivity (29) under high pressure ternary mixed gas (CO₂/H₂S/CH₄) feeds. Defect-free asymmetric hollow fiber membranes were formed and appropriate crosslinking conditions were determined, allowing for the characterization of these fibers under realistic sour gas feed conditions. Also, a PDMS post-treatment was used to give ultra-high permselectivity for aggressive feeds. Using several mixed gas feeds containing high concentrations of CO₂ and H₂S at feed pressures up to 700 psig, it is shown that the crosslinked asymmetric hollow fiber membranes developed and manufactured through this work are capable of maintaining excellent separation performance even under exceedingly taxing operating conditions. For example, CO₂/CH₄ and H₂S/CH₄ permselectivity values of 47 and 29, respectively, were obtained for a 5% H₂S, 45% CO₂, 50% CH₄ feed at 35°C with 700 psig feed pressure. An extremely aggressive 20% H₂S, 20% CO₂, 60% CH₄ mixed gas feed with 500 psig feed pressure was also used; the maximum CO₂/CH4 and H₂S/CH₄ permselectivity values were found to be 38 and 22, respectively.

Os grandes campos de petróleo offshore recentemente descobertos na camada pré-sal, localizada no sudeste do Brasil, representam um avanço significativo da participação brasileira nas reservas mundiais de hidrocarbonetos, que ainda são a principal matriz energética mundial. Nesse cenário, torna-se importante o desenvolvimento da produção desses campos. Um dos principais desafios tecnológicos da exploração desses campos é o processamento do gás natural associado, que possui altos teores de dióxido de carbono CO2. Esse contaminante deve ser separado para possibilitar a injeção no reservatório e/ou o escoamento desse gás através de dutos submarinos, dadas as restrições na legislação ambiental. Nas plantas de processamento instaladas no convés de grandes embarcações, são previstas instalações para a separação do CO2 e a remoção de umidade do gás a fim de evitar a formação de hidratos e a corrosão acentuada das linhas de escoamento, pois tanto a injeção quanto a exportação do gás são realizadas em condições de pressão e temperaturas extremas. Nesse contexto, o conhecimento acurado das condições em que se forma uma fase aquosa líquida é importante para garantir a viabilidade técnica e de segurança dessas operações. Considerando a relevância do assunto e as limitações da literatura para os cenários enfrentados no pré-sal brasileiro, esse trabalho tem o objetivo de fazer um estudo abrangente do equilíbrio de fases em sistemas contendo hidrocarbonetos em fase gasosa com altos teores de CO2 e traços de água, visando à obtenção de modelo para cálculo do ponto de orvalho da água. O uso de modelos rigorosos baseado na teoria dos fluidos associativos (PC-SAFT) mostrou-se adequado para o cálculo das condições de saturação em amplas faixas de pressão e temperatura. Com base em dados experimentais publicados foi possível fazer um ajuste preciso dos parâmetros de interação binária da equação de estado PC-SAFT. Como resultado, obteve-se um modelo capaz de descrever o comportamento de fases em misturas de hidrocarbonetos com composição próxima das encontradas no pré-sal brasileiro. / The giant offshore petroleum fields recently discovered in the pre-salt layer on the southeast of Brazil represent a significant increment in the Brazilian share of the global hydrocarbon reserves, which is still the most important energetic matrix. In this scenario, the development of production for these petroleum fields becomes important. One of the main technological challenges posed by these fields is the processing of the associated gas, which contains high amounts of carbon dioxide (CO2). Due to environmental laws, this contaminant must be separated to allow the injection back into the reservoir and/or the gas flow through subsea pipelines. The gas processing plants installed on large vessels comprise facilities that remove CO2 and moisture from natural gas, to prevent hydrate formation and severe corrosion throughout the pipelines, as both gas injection and gas exportation are performed in extreme pressure and temperature conditions. Thus, the accurate knowledge of conditions in which aqueous liquid phases are formed is important to ensure the technical viability and operational safety of these operations. Considering the relevance of this subject and the limitations of published works for the Brazilian pre-salt scenario, this work presents a comprehensive study on the phase equilibrium in systems with hydrocarbons in gas phase with high content of CO2 and traces of water, aiming at developing a model to calculate the dew point of water. The use of a rigorous method based on the associating fluid theory (PCSAFT) has shown to be appropriate to calculate the saturation condition for a large range of pressure and temperature. Based on the experimental data published, the fitting of the binary interaction parameter from the PC-SAFT equation of state was carried out. The resulting model was able to describe the phase behavior of hydrocarbon mixture with composition similar to those found in the Brazilian pre-salt.

It had been shown that the transport properties of CMS membranes varies as a function of H₂S exposure making the conditioning protocol an important step in identifying the steady state properties of CMS membranes. In this study the conditioning of CMS membranes with H₂S was studied for the determination of the acid gas steady state transport properties. The conditioned steady state has been shown to be the same state for both an extended conditioning protocol using high pressure mixed gas and a rapid conditioning protocol using pure H₂S. The rate of conditioning does vary between the two conditioning protocols as the rapid conditioning protocol takes 48 hours less to reach the conditioned steady state. The results of this study also show that oxygen doping during the formation of the CMS membrane affects the final, conditioned steady state transport properties.

Os grandes campos de petróleo offshore recentemente descobertos na camada pré-sal, localizada no sudeste do Brasil, representam um avanço significativo da participação brasileira nas reservas mundiais de hidrocarbonetos, que ainda são a principal matriz energética mundial. Nesse cenário, torna-se importante o desenvolvimento da produção desses campos. Um dos principais desafios tecnológicos da exploração desses campos é o processamento do gás natural associado, que possui altos teores de dióxido de carbono CO2. Esse contaminante deve ser separado para possibilitar a injeção no reservatório e/ou o escoamento desse gás através de dutos submarinos, dadas as restrições na legislação ambiental. Nas plantas de processamento instaladas no convés de grandes embarcações, são previstas instalações para a separação do CO2 e a remoção de umidade do gás a fim de evitar a formação de hidratos e a corrosão acentuada das linhas de escoamento, pois tanto a injeção quanto a exportação do gás são realizadas em condições de pressão e temperaturas extremas. Nesse contexto, o conhecimento acurado das condições em que se forma uma fase aquosa líquida é importante para garantir a viabilidade técnica e de segurança dessas operações. Considerando a relevância do assunto e as limitações da literatura para os cenários enfrentados no pré-sal brasileiro, esse trabalho tem o objetivo de fazer um estudo abrangente do equilíbrio de fases em sistemas contendo hidrocarbonetos em fase gasosa com altos teores de CO2 e traços de água, visando à obtenção de modelo para cálculo do ponto de orvalho da água. O uso de modelos rigorosos baseado na teoria dos fluidos associativos (PC-SAFT) mostrou-se adequado para o cálculo das condições de saturação em amplas faixas de pressão e temperatura. Com base em dados experimentais publicados foi possível fazer um ajuste preciso dos parâmetros de interação binária da equação de estado PC-SAFT. Como resultado, obteve-se um modelo capaz de descrever o comportamento de fases em misturas de hidrocarbonetos com composição próxima das encontradas no pré-sal brasileiro. / The giant offshore petroleum fields recently discovered in the pre-salt layer on the southeast of Brazil represent a significant increment in the Brazilian share of the global hydrocarbon reserves, which is still the most important energetic matrix. In this scenario, the development of production for these petroleum fields becomes important. One of the main technological challenges posed by these fields is the processing of the associated gas, which contains high amounts of carbon dioxide (CO2). Due to environmental laws, this contaminant must be separated to allow the injection back into the reservoir and/or the gas flow through subsea pipelines. The gas processing plants installed on large vessels comprise facilities that remove CO2 and moisture from natural gas, to prevent hydrate formation and severe corrosion throughout the pipelines, as both gas injection and gas exportation are performed in extreme pressure and temperature conditions. Thus, the accurate knowledge of conditions in which aqueous liquid phases are formed is important to ensure the technical viability and operational safety of these operations. Considering the relevance of this subject and the limitations of published works for the Brazilian pre-salt scenario, this work presents a comprehensive study on the phase equilibrium in systems with hydrocarbons in gas phase with high content of CO2 and traces of water, aiming at developing a model to calculate the dew point of water. The use of a rigorous method based on the associating fluid theory (PCSAFT) has shown to be appropriate to calculate the saturation condition for a large range of pressure and temperature. Based on the experimental data published, the fitting of the binary interaction parameter from the PC-SAFT equation of state was carried out. The resulting model was able to describe the phase behavior of hydrocarbon mixture with composition similar to those found in the Brazilian pre-salt.

The goal is of this project was to identify principles to guide the development of high performance dense film membranes for natural gas sweetening using hydrogen sulfide and carbon dioxide gas mixtures as models under aggressive sour gas feed conditions. To achieve this goal, three objectives were developed to guide this research. The first objective was to study the performance of cellulose acetate (CA) and an advanced crosslinkable polyimide (PDMC) dense film membrane for H₂S separation from natural gas. The second objective was to engineer those polymers to produce membrane materials with superior performance as measured by efficiency, productivity, and plasticization resistance, and the third objective was to determine the separation performance of these engineered membrane materials under more aggressive, realistic natural gas feeds, and to perform a detailed transport analysis of the factors that impact their performance. Work on the first objective showed that in neat CA, penetrant transport is controlled by both the solubility and mobility selectivity, with the former being more dominant, leading to a high overall CO₂/CH₄ (33) and H₂S/CH₄ (35) ideal selectivities. However, in uncrosslinked PDMC, H₂S/CH₄ selectivity favored sorption only, whereas CO₂/CH₄ selectivity favored both mobility and sorption selectivity, leading to a high CO₂/CH₄ (37) but low H₂S/CH₄ (12) ideal selectivities. However, the latter polymer showed more plasticization resistance for CO₂. In the second objective, both materials were engineered. A new technique referred to as “GCV-Modification” was introduced in which cellulose acetate was grafted using vinyltrimethoxysilane (VTMS), then hydrolyzed and condensed to form a polymer network. PDMC was also covalently crosslinked to enhance its performance. GCV-Modified CA showed significant performance improvements for H₂S and CO₂ removal; the permeability of CO₂ and H₂S were found to be 139 and 165 Barrer, respectively, which represented a 30X and 34X increase compared to the pristine CA polymer. The H₂S/CH₄ and CO₂/CH₄ ideal selectivities were found to be 39 and 33, respectively. Crosslinked PDMC showed a higher CO₂/CH₄ selectivity of 38 with a better plasticization resistance for CO₂ and H₂S. In the third objective, these materials were tested under aggressive ternary mixtures of H₂S/CO₂/CH₄ with both vacuum and nonvacuum downstream. Even under aggressive feed conditions, GCV-Modified CA showed better performance vs. PDMC, and it remained were fairly stable, making it a potential candidate for aggressive sour gas separations, not only because of its significantly higher productivity, which will help decrease the surface area needed for separation, thereby reducing operating costs, but also because of the lower cost of the raw material GCV-Modified CA compared to PDMC.

The purpose of this study was to examine the performance of several generic types of organic protective coatings as a corrosion protection method for the interior of subsea pipelines in sour gas media. The sour gas environment was simulated in the laboratory by the use of an Autoclave and the performance of the organic coatings was studied via the use of Electrochemical Impedance Spectroscopy (EIS) and Linear Polarization Resistance (LPR) tests to determine the coatings resistance, capacitance and corrosion behavior before and after the exposure to sour gas environment. The coating degradation and the corrosion products formed were examined by the use of SEM/EDS. The results indicated that both FBE and Novolac Epoxy coatings had excellent adhesion properties and chemical resistance. The Amine-Cured Novolac Epoxy coating exhibited good adhesion properties and chemical resistance. However, the Phenolic Epoxy coating started to degrade over time and corrosion took place under the coating.