Tubular string temperature and pressure are important parameters in string mechanics analysis. Thus, accurately calculating temperature and pressure in the injection process is fundamental for analyzing the tubular string mechanics of CO₂ injection wells. Based on the S-W equation of state and Vesovic models, we modeled the physical properties of CO₂. Then, based on the physical properties of CO₂, combined with the theory of heat transfer and three conservation laws, a temperature–pressure coupling model of a tubular string was established. Lastly, the temperature and pressure field distributions of the G66X1 well were determined using the alternating iteration method. According to a comparison of the established model and the actual data, the maximum error in predicting temperature was 4.1% and the maximum error in predicting pressure was 2.3%; thus, the model exhibits a high level of accuracy. In the final section, the model was used to study the influence of injection temperature on the tubular string temperature and pressure field distribution. Next, we studied the influence of the injection time, displacement, and pressure on the bottom hole temperature. This study provides a reference for predicting the wellbore temperature and pressure in CO₂ injection wells.

Wellbore liquid loading is a major issue in the later stages of gas well development, particularly for low-permeability gas fields such as shale gas and tight gas, severely affecting the normal production of gas wells. Accurately predicting the onset of wellbore liquid loading and implementing preventive measures are crucial for ensuring the normal production of gas fields. Therefore, based on the gas–liquid-carrying mechanism in gas wellbores and the flow patterns of gas–liquid two-phase flow in inclined wells, the criterion for gas critical liquid-carrying is determined by the shear stress between the liquid film and the pipe wall being zero. By considering the relative velocity between gas and liquid phases, porosity, and the distribution of velocity across the cross-section through the gas–liquid momentum balance equations, a gas critical liquid-carrying velocity model based on the drift model is established. Field data are used to compare the proposed model with four existing liquid-loading prediction models using the misjudgment rate, mean relative percentage error, and mean absolute percentage error as evaluation metrics for model accuracy. The results show that the proposed model outperforms the other models, with a misjudgment rate of 2.99%, mean relative percentage error of 3.83%, and mean absolute percentage error of 4.12%.