Desenvolvimento e avaliação de soluções ácidas contendo Nonilfenóis Polietoxilaados e etanol para acidificação de carboidratos
During the different stages of well development and reservoir exploitation, there is the possibility of the occurrence of unwanted phenomena that alter the permeability of the near-wellbore region (formation damage), compromising the production. The well stimulation techniques seek to bypass or reve...
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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/123456789/57842 |
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| Resumo: | During the different stages of well development and reservoir exploitation, there is the possibility of the occurrence of unwanted phenomena that alter the permeability of the near-wellbore region (formation damage), compromising the production. The well stimulation techniques seek to bypass or reverse this damage and, consequently, increase production. Matrix acidizing in carbonates consists of injecting an acidic fluid into the well to increase its production by dissolving the rock matrix itself, creating channels known as
wormholes. Hydrochloric acid (HCl) is the most used substance to stimulate both production and injection wells in carbonate reservoirs. However, the high reaction rate of HCl with carbonate reduces its penetration into the rock formation since the acid reacts excessively with the rock surface (face dissolution). Thus, to minimize acid consumption and increase the depth of wormholes, it is necessary to develop stimulation fluids containing additives that reduce the acid dissolution rate of the carbonate matrix. The present study aims to develop and evaluate new acid solutions containing nonionic surfactants and ethanol to delay the dissolution of calcium carbonate in the acidification process of carbonate rocks, providing deeper wormholes in the reservoir. To do so, characterization analyses were carried out for the developed fluids and carbonate samples. In addition, compatibility tests of the components of the developed fluids, reactive flow in porous media tests (injection of the formulations in rock samples) and computerized microtomography of acidified rocks were performed. As a result, it was found that fluids containing surfactants with a higher degree
of ethoxylation promoted a more significant increase in viscosity and in the delay of the carbonate rock dissolution. In the reactive flow in porous media tests, regarding the minimum pore volume to breakthrough (optimal PVbt), the formulations obtained similar results to those of 15% HCl but at flow rates 4 to 8 times lower. These low flow rates are more consistent with those observed in field treatments. Furthermore, the formulations produced wormhole patterns that are similar to the dominant one over a broader injection rate range. Therefore, the studied formulations provided promising results in the reactive flow in porous
media tests and presented some interesting characteristics for application in acid stimulation
treatments |
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