Modelagem e simulação termodinâmica da precipitação de calcita em condições de poço

• Autor(a) principal: Cosmo, Rafael de Paula
• Data de Publicação: 2013
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)
• Texto Completo: http://repositorio.ufes.br/handle/10/5334
• topic: Scaling; Calcium carbonate; Calcite; Thermodynamic; Engenharia/Tecnologia/Gestão; Precipitação (Química); Carbonato de cálcio; Calcita; Termodinâmica; 620.9

Oil will still be the matrix of higher energy demand in Brazil and around the world for decades. Easily accessible oil deposits are increasingly scarce, and therefore, more challenging reserves will require innovative solutions and technologies. Among the challenges imposed to the process, are those related to flow assurance, especially saline fouling of carbonate origin, noticeably calcite. Several phenomena occur for effectivation of the fouling, such as nucleation, crystal growth, particle agglomeration, transport and surface adhesion, among others. The forecast of fouling only will represent the reality if all phenomena are accurately described. In this sense we pursued to model thermodynamically, for well conditions, the initial stage of fouling, which is the nucleation of crystals from solution. One of the results obtained was an explicit equation, as a function of pressure and temperature, of the equilibrium constant for the reaction which is expected to occur under the conditions investigated: CaCO3(s) + H2O(l) + CO2(aq)  Ca2+ (aq) + 2 HCO3 – (aq). In order to quantify the content of calcite likely to precipitate from the solution, a methodology was developed not only to measure the mass precipitated, but also to distinguish the origin factor of precipitation. As a result it was verified that the changes in the thermodynamic conditions little affect the calcite precipitation, but greatly affect the solubility of the carbon dioxide, and this really influences in a preponderant manner the crystallization of the carbonate salts, because it contributes to 60% to 90% of the total content precipitated.