Ability of a one-part granite-based geopolymer sealant to withstand exposure to CO2 with H2S or H2SO4 in the presence of H2O

The long-term integrity of wellbore sealants is critical for successful CO2 storage in geological reservoirs. This paper addresses the durability of a one-part, granite-based geopolymer (GP) sealant batch-exposed to CO2 and H2O, with or without H2S or H2SO4 for up to 16 weeks. Microstructural and mineralogical changes were then characterized using a wide range of analytical techniques. Results show that exposure led to an increase in the material’s crystalline content. Vaterite was the dominant early carbonate in all cases. This then transformed primarily into aragonite in samples exposed to clean CO2, while calcite was more prominent in samples exposed to CO2 with H2S or H2SO4. The matrix's crystallinity was further enhanced through consecutive reactions of aluminosilicate gels. Even though exposure resulted in elevated sulfur contents, no sulfur-bearing minerals were detected. Despite these alterations, the GP maintained its integrity during exposure to chemically aggressive conditions, demonstrating its durability as a sealant.