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Investigation of Water Salinity Effect on Asphaltene Precipitation Using PC-SAFT EOS

Amanabadi, Javad | 2021

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 54353 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Jamshidi, Saeed
  7. Abstract:
  8. In this study, for investigation of water salinity effect on asphaltene modeling, PC-SAFT equation of state has been used. All steps of modeling have been done by C sharp programming language software. Nghiem model has been used for modeling of asphalting pure solid. In this model, the heaviest component is split into two precipitating and nonprecipitation parts that their physical properties are the same in each part. Furthermore, to determine the exact mechanism of asphaltene precipitation, an oil model (Asphaltene+heptan+tuloene) in the presence of different water brine such as synthetic brine (with MgCl2, CaCl2, and Na2SO4 salts), seawater) ten and two times diluted), and formation water is used. Three adjustable parameters in the Particle Swarm Optimization tool are used to minimize the AAD percentage between experimental and modeling. asphalten’s fugacity in the pure solid, interaction between asphaltene and ions, and interaction of asphaltene with water are considered as adjustable parameters. According to the chelation process, the interaction between asphaltene and cations is considered more than asphaltene with anions. The first sensitivity analysis for fugacity of asphaltene was conducted that the trend of fugacity has minimum or maximum value. Then the PSO algorithm is executed. On the other hand, due to the low solubility of hydrocarbon compounds in the water phase, determining the whole amount of asphaltene precipitation in each step is very sensitive. To ensure that, the fraction of participated component in each step must be reduced by ε and then repeat the calculations, which is much less than the amount considered in the estimates of the effect of hydrocarbon gases on asphaltene precipitation. As a result, in low concentrations of salts, due to the salting-in effect, the asphaltene molecules migrate to the oil/water interface, leading to decreasing asphaltene precipitation. Beyond this concentration, the asphalting precipitation due to the salting-out effect increased. In conclusion, modeling asphaltene precipitations in the presence of different salinity can reduce the asphaltene precipitating problems
  9. Keywords:
  10. Asphaltene Precipitation ; Particles Swarm Optimization (PSO) ; Perturbed Chain From of the Statistical Associating Fluid Theory (PC-SAFT)State Equation ; Calcium Chloride ; Sodium Sufate Salts ; Magnesium Chloride Salts

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