O2驱注入管柱温度压力耦合模型建立及其敏感性因素研究

In order to accurately analyze the stress of CO2 flooding injection string, it is necessary to consider the phase distribution of CO2 fluid in the injection string, and reasonably predict the temperature field and pressure field distribution of CO2 flooding injection string. Firstly, the coupling differential equations of temperature, pressure and physical parameters of CO2 flooding injection string were established by three conservation laws. Then, according to the calculation steps of fourth-order Runge Kutta algorithm, MATLAB program was compiled to analyze the temperature field and pressure field of four CO2 flooding injection strings in an oilfield. Finally, the sensitivity factors of temperature field and pressure field distribution of CO2 flooding injection string were analyzed. The results indicate that in the process of CO2 flooding injection, the temperature and pressure of CO2 flooding injection string increase approximately linearly with the increase of formation depth. The fluid temperature exceeds the critical temperature by 31 ℃ after 1 400 m of the string, and the phase state of CO2 fluid changes to supercritical state. The temperature field distribution of injection string is most significantly affected by the injection rate of CO2 fluid, and its sensitivity coefficient reaches 3.1. The pressure field distribution of injection string is most significantly affected by the injection pressure of CO2 fluid, and its sensitivity coefficient reaches 1.25.