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Cinzas volantes e ze?litas sint?ticas na composi??o da pasta de cimento classe G e degrada??o por CO2 em condi??es de armazenamento geol?gico de carbonoLedesma, Roger Braun 15 January 2018 (has links)
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Previous issue date: 2018-01-15 / Developing technologies for the capture and geological storage of CO2 has
been a constant challenge of the scientific community in the search for solutions that
can reduce the environmental impacts caused by the release of this gas into the
atmosphere. However, its storage in depleted oil wells has been shown to be a very
important point, since the materials applied in wells can suffer degradation in the
presence of CO2 in the supercritical state and at high pressures. The objective of this
work is to evaluate the performance of the class G cement paste used in cementation of
wellbore under conditions of geological carbon storage with replacement of part of the
cement by pozoanic materials such as fly ash from the fossil fuel burning of the
Candiota Thermoelectric Plant, and synthetic zeolites (4A-1 e 4A-2). The contents of the
pozalanas used in substitution of the cement were 5% and 10% in weight. The medium
in which samples were submitted for degradation tests was CO2 saturated water at 15
MPa pressure and 90 ?C for 7 and 14 days. Scanning Electron Microscopy (SEM), XRay
Diffraction (XRD) and compressive strength tests were the characterization
techniques used in this work. The results showed that the use of fly ash increased the
compressive strength of the samples after 14 days, mainly for higher percentage of
cement replacement by this material (10%), but its chemical degraded layer increased.
In case of zeolites 4A-1 use, a lower compressive strength was observed compared to
the standard paste, but the degraded layer was reduced. When zeolites 4A-2 were used
significant loss of compressive strength was observed from 7 to 14 days, mainly for the
proportion of the mixture of 10% and its degraded layer also reduced. / Desenvolver tecnologias para a captura e armazenamento geol?gico de CO2
tem sido um desafio constante da comunidade cient?fica na busca de solu??es que
possam reduzir os impactos ambientais provocados pela libera??o desde g?s na
atmosfera. Por?m, seu armazenamento em po?os depletados de petr?leo tem se
mostrado o ponto mais desafiador, pois os materiais aplicados nestes po?os podem
sofrer degrada??o na presen?a de CO2 em estado supercr?tico e em altas press?es.
Este trabalho tem como objetivo avaliar o desempenho da pasta de cimento classe G,
utilizada na cimenta??o e tamponamento dos po?os, em condi??es de armazenamento
geol?gico de carbono com substitui??o de parte do cimento por materiais pozol?nicos.
O material utilizado foi as cinzas volantes, oriundas da queima de carv?o mineral da
Usina Termoel?trica de Candiota, e ze?litas 4A comerciais sint?ticas (4A-1 e 4A-2). Os
teores utilizados das pozalanas em substitui??o ao cimento foram 5% e 10% em
massa. O meio em que foram submetidas as amostras foi de ?gua saturada com CO2 a
15 MPa de press?o a 90? C por 7 e 14 dias. A Microscopia Eletr?nica de Varredura
(MEV), a Difra??o de Raios X (DRX) e o teste de resist?ncia ? compress?o foram as
t?cnicas de caracteriza??o utilizadas neste trabalho. Os resultados obtidos mostram
que o uso de cinzas volantes aumentou aos 14 dias a resist?ncia ? compress?o das
amostras, principalmente para maior a porcentagem de substitui??o do cimento por
este material (10%), por?m a camada alterada quimicamente aumentou. Quando
utilizadas as ze?litas 4A-1, notou-se uma menor resist?ncia ? compress?o que a pasta
padr?o, mas a camada degradada reduziu. No caso das ze?litas 4A-2, foi constatada a
perda significativa de resist?ncia ? compress?o dos 7 para 14 dias, principalmente para
a amostra contendo 10% dessa zeolita, sendo que a camada alterada quimicamente
tamb?m reduziu.
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