Chemical degradation of reinforced epoxy‐cement composites under CO₂‐rich environments

Long‐term wellbore integrity is crucial to prevent leakage of CO₂ and to ensure performance and safety of carbon geologic storage. One of the concerns is the degradation of Portland cement due to its exposure to CO₂. In this study, Portland cement paste composed of three reinforced‐epoxy resins (talc, agalmatolite, and montmorillonite clay as filler) was compared to unmodified cement paste with respect to CO₂ resistance. CO₂ degradation experiments were conducted with aqueous CO₂ at elevated pressure (50 bar) and temperature (70°C) in order to mimic wellbore conditions. Epoxy cement composites were characterized by phenolphthalein test, field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and mechanical compression test. The preparation method of the composites is the parameter likely to affect the CO₂ resistance than curing conditions (natural and thermal). Addition of up to 5% of montmorillonite clay reinforced‐epoxy resins provides an improvement in CO₂ resistance over unmodified Portland cement paste, showing to be a promising alternative to obtain suitable materials for use in wellbores in CO₂ sequestration reservoirs. POLYM. COMPOS., 39:E2234–E2244, 2018. © 2017 Society of Plastics Engineers