Estudo de estabilidade de petróleos e modelagem do parâmetro de solubilidade de petróleos e asfaltenos

• Autor(a) principal: Santos, David Caetano
• Data de Publicação: 2017
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/11884
• topic: Crude oil, asphaltene; solubility parameter; internal pressure; Petróleo; asfalteno; parâmetro de solubilidade; pressão interna; CNPQ::ENGENHARIAS::ENGENHARIA QUIMICA::TECNOLOGIA QUIMICA

The development of models for the prediction of the solubility parameter of crude oils and heavy oil fractions is the main motivator of this study. This property has become a reference for several applications in the petroleum industry and it has been applied mainly for the prediction of compatibility and stability of crude oils. The solubility parameter is a thermodynamic property that is originated from the solution theory - the so-called Regular Solution Theory - idealized by J. H. Hildebrand and it can be easily calculated from the enthalpy of vaporization and mixture composition data. However, obtaining data of these two properties for crude oils is a critical step since they are extremely complex mixtures in terms of their composition and have non-vaporizing species, which are precisely the main responsible for problems related to incompatibility and instability of crude oil mixtures. Thus, in this thesis, several ratifications were made related to an experimental method for predicting solubility parameter of crude oils, which is based on asphaltene flocculation data. The numerical value obtained from this method is considered a pseudo-experimental data, representing a useful tool to measure the quality results obtained from the new models proposed in this thesis. Thereby, the thermodynamic information between the cohesive energy and the internal pressure was used to calculate the solubility parameter of crude oils. Although this relationship has already been addressed by several works, it has not yet been systematically explored for crude oils. Speed of sound, density and heat capacity at constant pressure data of pure hydrocarbons were used to adjust the models. Therefore, thermodynamically consistent models are proposed to estimate the solubility parameter of crude oils using only single-phase properties rather than the usual vaporization data. New empirical correlations based on the relation of potential energy and on simplifications of the analytical expression of internal pressure are also proposed. The thermodynamic modeling of experimental asphaltene flocculation data was performed from modifications on the so-called solubility models . As a result, these modifications coupled with adequate numerical strategies yielded good qualitative and quantitative results that had not yet been demonstrated in the literature. Finally, a cubic equation of state parameterized only with data from single-phase properties plus the solubility parameter data was developed. From this Equation, in addition to the solubility parameter, the coefficient of isothermal compressibility, coefficient of thermal expansion, speed of sound and density data of heavy and complex hydrocarbons were adequately fitted. In addition, the proposed cubic equation predicts a substance-dependent critical compressibility factor. As far as it can be ascertained, no cubic equation of state available in the literature was able to predict the solubility parameter, while maintaining an adequate description of the PVT properties, especially the compressibility of liquids. These results are important because they demonstrate that differentiated parameterization strategies for this type of equation are effective to advance in applications in which cubic equations of state have several limitations