Avaliação das propriedades mecânicas e microestruturais de pastas de cimento portland formuladas com aditivos mineral quando submetidas a altas temperaturas e pressão em poços de petróleo
The cementing operation consists of a work of extreme importance to the phase of drilling and completion of petroleum wells and has great impact on well productivity.The injection of steam in heavy oil wells is used to improve the recovery causing loss of hydraulic insulation between the layers of t...
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| Formato: | doctoralThesis |
| Idioma: | pt_BR |
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Universidade Federal do Rio Grande do Norte
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| Endereço do item: | https://repositorio.ufrn.br/handle/123456789/49574 |
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| Resumo: | The cementing operation consists of a work of extreme importance to the phase of drilling and completion of petroleum wells and has great impact on well productivity.The injection of steam in heavy oil wells is used to improve the recovery causing loss of hydraulic insulation between the layers of the reservoir, which increases production costs. Studies show that the calcium silicate hydrate (C-S H) is the main product of the cement hydration and main responsible for the resistance of the cement slurries. Presenting good stability at temperatures up to 110 ° C, however for temperatures above these the C-S-H is converted to the phase α-C2SH with a high ratio Ca/Si that has characteristics of low mechanical resistance and high permeability. The use of materials with high silica concentration reduces the ratio CaO/SiO2 leaving rates near or below 1.The aim of this study was to evaluate the formation of calcium silicate hydrate in different formulations cement slurries when submitted to high temperatures after they were formulated with additives mineral with: Porcelain Stoneware waste (RC), Sugarcane biomass (CBC) and metakaolin (MK).All formulations were compared to cement slurry pure with reference and the other with a composition based on 40% silica flour (SF), material used in the petroleum industry as additives anti-regression. After the cement slurries being cured at a temperature of 38°C for 28 days, were carried out compressive strength testing and X-ray diffraction to examine the formation of the C-S-H in substitution the calcium hydroxide being repeated tests after curing of 280°C for 3 days.Although the pastes formulated with RC have presenting excellent results at 38 ° C when subjected to 280 ° C retrogression was observed.The paste formulation containing CBC when formulated with a ratio of 40 mass% in relation to cement maintained the resistance above 17 MPa which is the minimum required by API standards, confirming that shows the literature.Finally MK showed superior results compared to the CBC as SF even at concentrations of 20% compared to the mass of cement can be explained both by the high rate of amorphicity of metakaolin as the formation of the crystalline phase Bicchulite (Ca8(Al2SiO6)4(OH)8) which is different from the phases formed in the paste containing SF and CBC. The presence of Bicchulite was confirmed by scanning electron microscopy with the aid of EDS.It was concluded that small deviations of chemical concentration and region amorphicity of a mineral additive can be crucial to determine the capacity of a chemical reaction with the calcium hydroxide of the pastes hydrated. |
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