Abstract: Under thecarbon capture, utilization and storage (CCUS) well, the oil well cement will be carbonized and corroded due to the long-term action of downhole high temperature, high pressure and highly acidic fluid, resulting in the failure of the cement sheath. In order to simulate the carbonation and corrosion environment of CO₂ geological storage well, the main single ore mineral calcium silicate (C₃S) of oil well cement was placed under different temperatures (30 ℃, 60 ℃, 90 ℃) and sealed 8.0 MPa gas or liquid phase CO₂ carbonization environment. XRD and TGA were used to analyze the influence of C₃S in cement single ore by CO₂ corrosive environment. According to the infiltration theoretical model of unsteady Fick diffusion, a mathematical model of the quantitative analysis results of corrosion products and corrosion age was established, and the product formation coefficient of C₃S after being corroded by CO₂ was obtained by fitting, so as to evaluate the influences of different CO₂ corrosion factors on C₃S. The results show that the increase of temperature significantly aggravates the corrosion of C₃S and leads to the dissolution phenomenonin the gas phase environment of CO₂. While in the liquid phase environment of CO₂, the high temperature (90 ℃) makes the C₃S hydration reaction intensify, forming a retardation layer and slowing down the CO₂ corrosion rate to C₃S.

Key words: cement single ore C₃S, CO₂ corrosion, CCUS, corrosion kinetics model, penetration theory, phase change