The effects of solubility of acid gases such as H₂S and CO₂ in liquid medium on the corrosion and environmental fracture (SSC and HIC) of tube and casing in different wells in the same block or in different sections of the same wells were investigated. On the basis of the test device simulating the solubility of CO₂ in the environment of oil and gas wells, the CO₂ solubility tests under different temperatures, pressures and salinities were carried out. The gray correlation method was used to analyze the sensitivity of CO₂ solubility from three aspects of temperature, pressure and salinity, through which the correlation between CO₂ solubility and temperature, pressure and salinity were obtained. Based on the experimental data and the improved P-R EOS, the method of combining the fugacity coefficient model and the mixing rule was used to fit and analyze the correlation between the prediction results and the binary interaction parameters in the model, and the binary interaction parameters were obtained to modify and improve the prediction model of CO₂ solubility in formation water. Phase equilibrium data of CO₂ formation water system under experimental temperature (303.15-363.15 K), pressure (5-30 MPa) and salinity (0-0.7 mol/kg) were calculated. The results show that there is a transition pressure when CO₂ solubility changes with pressure (the transition pressure in this experiment is 15 MPa). Under the transition pressure, CO₂ solubility increases faster with pressure; the temperature is the main controlling factor of CO₂ solubility, followed by pressure and salinity; the CO₂ dissolution process is controlled by the mixture of temperature, pressure and salinity, and its solubility change trend mainly depends on the dissolution rate and escape speed of CO₂ gas molecules in aqueous solution. The comparison between experimental data and prediction results of CO₂ solubility shows that the optimized prediction model is accurate and reliable.