Análise da Carbonatação em Geopolímeros para aplicação em poços de Petróleo

Abstract

Geopolymers have been widely studied as a promising alternative to Portland cement for well cementing applications in the oil and gas industry. Their synthesis does not involve calcination processes, resulting in a significant reduction in associated CO₂ emissions, making them a more environmentally sustainable option. It is worth noting that Portland cement production is responsible for approximately 7% of global anthropogenic carbon dioxide emissions. In addition to the lower environmental impact, geopolymers exhibit superior physico-chemical properties in several aspects, including higher compressive strength, lower permeability, greater compatibility with drilling fluids, and enhanced resistance to acidic environments, such as those containing carbon dioxide (CO₂) and hydrogen sulfide (H₂S), commonly found in deep geological formations. However, within the context of oil well cementing, carbonation is one of the main degradation mechanisms affecting cementitious materials, potentially compromising the structural integrity and long-term durability of the cement sheath. Considering this issue, the present study conducted an in-depth literature review on the behavior of geopolymers under the carbonation process. It was concluded that geopolymer paste formulations with higher calcium content (such as calcium hydroxide) achieve lower carbonation depth due to the formation of calcium silicate hydrate (C–S–H) gel, which is the main component responsible for the mechanical strength of cementitious materials. Furthermore, it was found that the use of calcium in the composition ensures a higher pH, providing buffering against the carbon dioxide responsible for carbonation, and consequently promoting greater CO₂ neutralization within the paste. Therefore, geopolymeric cementitious paste formulations incorporating ground granulated blast furnace slag and calcium hydroxide play a promising role in enhancing the carbonation resistance of geopolymers.