A wellbore circulation flow model was proposed to couple calculate and analyze the flow field pressure parameter, temperature parameter and physical parameter of CO2 , in consideration of the influence of the axial heat transfer and the tem-perature change of sidewall rocks on the flow field. The results show that CO2 turns into supercritical state at the depth of 780 m in the tubing and it maintains the supercritical state in the annulus under experimental conditions. The pressure in the an-nulus is approximately in linear correlation with depth. The pressure change of CO2 is 36. 7 % smaller than that of water. In the tubing, the temperature change dominates the changes of properties of CO2 . However, the pressure change becomes the dominating factor in the annulus. The Reynolds number is as high as 106 in the annulus, which is in violent turbulence. The supercritical CO2 drilling shows advantages in the exploitation of reservoirs with narrow pressure windows.%考虑井筒轴向传热以及井壁围岩的温度变化对流场的影响,建立CO2井筒循环流动模型,实现对流场压力参数、温度参数与CO2物性参数的耦合计算与分析.结果表明:实验条件下连续管内CO2由液态转变为超临界态的临界井深为780 m,环空中CO2可始终处于超临界态;环空中压力剖面与井深近似呈线性相关,CO2的压降比水的小36.7%;连续管内物性参数的变化主要由温度的变化决定,环空中则取决于压力的变化;环空中雷诺数高达106,处于较强的紊流状态;超临界CO2钻井在窄密度窗口储层应用中具有优势.
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