چكيده به لاتين
Abstract:
Asphaltenes are the heaviest and most polarizable components of the crude oil. The phase behavior of these polydispersed components is significantly affected by the changes of the pressure, temperature and composition. Asphaltene in the crude oil - due to their precipitated and deposited potential - would cause problems such as decreasing the permeability and porosity of hydrocarbon reservoirs, changing the reservoir rock wettability, plugging the pipelines, sharply declining the refining and petrochemical processes and ultimately reducing the production rate. According to the precipitation of asphaltene is an essential specification for deposition, the significant amount of studies has been assigned to the understanding of conditions at which asphaltene precipitates from the crude oil. Thus To prevent and control the problems caused by asphaltene precipitation, it was tried to develop an appropriate thermodynamic models with accurate prediction ability in this thesis.
In this study, by monodisperse asphaltenes, Peng- Robbinson and PC-SAFT equation of state parameters assumption, optimization is performed based on the bubble point pressure, onset pressure and asphaltene precipitation calculations (by titration of dead oil with normal pentane solvent in atmospheric conditions).In order to figure out the asphaltenes behavior as poly-dispersed component, they are divided to three sub-fractions based on the used precipitating solvents and the calculations are repeated until adjust the parameters of both equations of state,. Comparing modeling results for monodisperse and polydispersed asphaltenes with experimental data of two Mexican crude oil samples i.e. C1 and Y3 shows that the best results is obtained in modeling of polydispersed asphaltenes with PC-SAFT equation of state. In this study, for the first time the polydispersed asphaltenes multisolid model is used.
In this thesis, the maximum mean absolute percentage error to predict the amount of precipitation occurs in modeling of monodisperse asphaltenes by using Peng- Robbinson equation of state and the minimum mean absolute percentage error to predict the amount of precipitation yields in the modeling polydispersed asphaltene by using the PC-SAFT equation of state. The maximum and minimum average absolute percentage error in the predicting the amount of precipitation, for crude oil sample C1, are 10.261 and 1.677 respectively, and , for crude oil sample Y3, are 4.145 and 0.9863 respectively.
Keywords: Asphaltene, Precipitation, PC-SAFT, Polydisperse, Multisolid
