A unified framework for calculating solid deposition from petroleum fluids including waxes, asphaltenes, hydrates and scales

Edmonds, Beryl; Moorwood, R.A.S.; Szczepanski, Richard

doi:10.1016/s0378-3812(99)00138-7

Cited by 24 publications

(14 citation statements)

References 13 publications

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“…The APE was evaluated based on the CPA approach with the commercial software "Multiflash ver 4.1 (released from Infochem Ltd.)" [30][31][32] . The Soave-Redlich-Kwong (SRK) cubic EoS 33 was applied for fluid characterization in models.…”

Section: Model and Work Flowmentioning

confidence: 99%

How Acid Gas Affects Asphaltene Precipitation Behavior

et al. 2014

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In a carbonate field, a gas injection scheme has been assessed to improve oil recovery through pressure maintenance and miscible displacement. The potential study assumed sequential application of several gas injection concepts: Raw Gas Injection (RGI) and Acid Gas Injection (AGI). Flow simulation studies of these concepts revealed a variety of compositional changes to the in-situ fluid depending on the injection scheme and composition of the injected gases. Compositional change is a common trigger of asphaltene instability; therefore, to ensure a robust gas injection development, it is important to evaluate the risk of asphaltene deposition. Due to high H 2 S concentrations in potential developments, it is difficult to take an experimental approach for evaluating gas-mixed asphaltene flow assurance. Hence, this paper will focus on one AGI scenario, and present how AGI impacts asphaltene precipitation behavior through numerical modeling analysis. Based on the asphaltene model established by applying Cubic Plus Association (CPA) equation of state (EoS), which was calibrated with the experimental measured asphaltene onset pressure (AOP), a new Binary Interaction Parameters (BIP) correlation between H 2 S and hydrocarbons was incorporated to evaluate variation of asphaltene precipitation envelope (APE) with periodical compositional change observed from the AGI flow simulation. Acid Gas (AG) was assumed to be 90mol% H 2 S and 10mol% CO 2 . The produced fluid H 2 S concentration used in this study was assumed to be~15mol%. During this study, H 2 S concentration was observed to increase up to 76mol% at a well located near AG injectors after long term flow simulation. In the APE sensitivity analysis that was independently conducted for each composition of H 2 S and CO 2 , the asphaltene model revealed the base APE shrunk as the H 2 S concentration increased while it expanded as the CO 2 concentration increased. As a result for the mixed compositions, the opposing effects on the APE offset each other; the AG addition produced a subsequent shrinking of the APE. In summary, this work supported acid gas injection from a thermodynamically asphaltene flow assurance point of view.

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Section: Model and Work Flowmentioning

confidence: 99%

How Acid Gas Affects Asphaltene Precipitation Behavior

et al. 2014

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“…Os parâmetros de caracterização usados na simulação dos hidratos são listados na Tabela 2, disponíveis na literatura (Englezos, 1987;Kelkar, 1998e Clennell, 2001). Entretanto o coeficiente cinético interfacial foi ajustado.…”

Section: Tabela 2 -Parâmetros Computacionais Considerados No Modelo Dunclassified

“…A temperatura de formação do hidrato foi determinada utilizando o diagrama de fase do gás natural, onde se pode relacionar a pressão com a temperatura de formação (Edmonds, 1999).…”

Section: Tabela 2 -Parâmetros Computacionais Considerados No Modelo Dunclassified

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Modelagem da cinética de formação de hidratos utilizando o Modelo do Campo de Fase em condições similares a dutos de petróleo

Oliveira¹,

Castro²,

Silva³

2008

Rem: Rev. Esc. Minas

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ResumoOs hidratos de gás são compostos cristalinos que se formam nas tubulações de petróleo causando problemas na sua extração e transporte. O Modelo do Campo de Fase mostra-se adequado para simular o crescimento dos hidratos de gás no interior de tubulações. O modelo fundamenta-se na solução simultânea das equações de transporte de energia e transformação utilizando-se da técnica de volumes finitos. Para a determinação da cinética de formação dos hidratos, deve-se determinar a mobilidade da interface, que reproduz a morfologia e a velocidade local de avanço da mesma. Baseando-se em resultados experimentais, alguns parâmetros do modelo foram ajustados para representar as condições de formação dos hidratos em um ensaio controlado. Objetivando a verificar a sensibilidade do Modelo do Campo de Fase, foram realizadas simulações variando-se o super-resfriamento e a nucleação. Os resultados de morfologia e cinética de formação dos hidratos foram comparados com resultados experimentais, apresentando boa concordância. Parâmetros tais como super-resfriamento e pressão foram decisivos no avanço da interface.Palavras-chave: Hidratos, campo de fase, cinéticos.

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“…,16,[27][28][29] Association theories, which are shown to be very promising tools for phase equilibria, especially provide an appealing method for modeling the fluid phases. Kontogeorgis et al30 presented hydrate dissociation calculations for simple gas mixtures in the presence of inhibitors.…”

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Applications of CPA to the Oil and Gas Industry

Kontogeorgis

Folas

2009

Thermodynamic Models for Industrial Applications

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There are various applications in the oil and gas industry where associating and/or oligomeric compounds are present. For these applications, it is expected that association models may be the preferred approach. Some examples are gas hydrate inhibitors, e.g. methanol and glycols, other flow assurance problems, e.g. related to asphaltenes, the variety of drilling, production and injection chemicals used in the oil industry, for which their environmental fate must be assessed and their use must be optimized, and finally the use of ethanol and other oxygenated polar compounds as additives in gasoline. Some of these examples are discussed below in more detail.Methanol is possibly the most important gas hydrate inhibitor. It suppresses gas hydrates but is often injected at a higher rate than necessary, due to uncertainties as to what the correct rate should be. Two important reasons for optimizing the amount of methanol used for inhibition (and keeping it to a minimum) are the cost of providing this chemical, especially on offshore platforms, and the fact that methanol is a toxic substance. The injection rate is directly related to the phase equilibria of mixtures containing oil, water and methanol. Moreover, the loss of hydrate inhibitor in the gas or condensate phases should be accurately known.Typically methanol is not being regenerated because it is relatively inexpensive. Common alternatives to methanol are the glycols, especially monoethylene glycol (MEG), which is added at rates up to 100% of the weight of water. Due to the high cost of MEG, regeneration is required, which, however, adds to the capital and operational cost as well as space requirements, especially for offshore installations. Hence, optimization of the MEG injection rate and minimizing the amount of MEG lost (mainly) in the hydrocarbon liquid and aqueous phases are directly related to the elimination of operational problems and decrease of cost.Another important problem where associating compounds are involved in the petroleum industry is related to the production and processing of natural gas. As previously discussed, the freezing diagrams of MEG-water and methanol-water have two eutectic points and an intermediate phase which indicates the formation of a solid (complex) hydrate between the two compounds. When natural gas is being produced from offshore fields, e.g. in the North Sea, and then transported to the gas plant, it is brought to sales gas specifications by a series of separators. In order to prevent the formation of gas hydrates during transportation and further processing, inhibitors such as ethylene glycol (MEG) are continuously added to the produced mixture (water and light hydrocarbons). Decreased efficiency has been observed in the separators at MEG concentrations, where according to the literature problem-free operation would be expected. This means that the concentration of ethylene glycol is high enough to inhibit formation of gas hydrates and low enough to prevent freezing of ethylene glycol. Experimental investigations indic...

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A unified framework for calculating solid deposition from petroleum fluids including waxes, asphaltenes, hydrates and scales

Cited by 24 publications

References 13 publications

How Acid Gas Affects Asphaltene Precipitation Behavior

How Acid Gas Affects Asphaltene Precipitation Behavior

Modelagem da cinética de formação de hidratos utilizando o Modelo do Campo de Fase em condições similares a dutos de petróleo

Applications of CPA to the Oil and Gas Industry

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