Estudo do Equilíbrio Multifásico de Misturas de Petróleo e Dióxido de Carbono em Condições de Alta Pressão e Alta Temperatura

• Ano de defesa: 2022
• Autor(a) principal: Medeiros, Hugo Andersson Dantas
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Palavras-chave em Português: Comportamento de fases; Petróleo; Dióxido de carbono; SWIR; Equilíbrio líquido-líquido
• Link de acesso: http://www.repositorio.ufc.br/handle/riufc/65243

In this work, a new phase transition data set for high opacity Brazilian pre-salt crude oil recombined with CO2 are presented by the intermediate of two different experimental techniques, i.e., indirect and direct, for pressure up to 90.00 MPa and temperature from 40.0 to 140.0 °C. The pressure-relative volume curve (PV curve) and NIR (near-infrared) transmittance signal were used as indirect methods. Moreover, direct observation was used as a direct method to identify a vapor or solid phase. Furthermore, an additional configuration for direct experimental has been proposed by using a high-pressure microscope (HPM) coupled with a SWIR (short-wave infrared) arrangement (camera and light source) to better observe complex phase transitions as either liquid-liquid, liquid-fluid, or solid-liquid-fluid. For crude oil + CO2 systems with lower gas content (37.9 and 50.0 mol % CO2) only vapor-liquid equilibria (VLE) were observed for all temperature domains investigated. However, for high gas content (76.6, 80.6, and 84.2 mol % CO2) and liquid-liquid equilibria (LLE) were detected above CO2 critical temperature. Nevertheless, a liquid-liquid expansion was observed with a pressure decrease, marked by a liquid drop size increase, resembling a vapor-liquid transition. A solid-phase was observed, and it could be related to asphaltene for crude oil + CO2 at high gas content with no redissolution by increasing pressure. Another solid phase was detected and was associated with wax, as fine solid dispersion morphology with slow redissolution kinetic against temperature. Firstly, after all the PVT experiments, the use PV curve along with light scattering and direct observation for vapor-liquid equilibrium. Secondly, HPM-SWIR as the visual technique was indispensable for high-pressure liquid-liquid equilibrium. Thirdly, HPM-SWIR along with light scattering technique for asphaltene precipitation above saturation pressure. Finally, HPM-SWIR as a visual technique is recommended to determine wax appearance temperature.