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 degrees 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. (c) 2017 Society of Plastics Engineers