中文摘要：

高温射流钻井过程中,高温流体在上返时易引起上部井壁岩石的裂解垮塌和钻柱持续高温,为实现安全高效钻井,提出了通过钻柱侧向注冷水的环空冷却方案,研究了射流速度、射流温度和冷水速度等参数对环空冷却效果的影响。研究结果表明：随着射流速度的增加,环空平均温度对射流速度的变化敏感性越来越弱,同时环空平均温度与射流温度呈线性关系。冷水速度存在某一临界值,该临界值与射流速度和井眼直径等因素有关,当冷水速度大于临界值时,既能够保证高温流体对井底的破岩效果,又可以对环空进行较好地冷却。研究中,临界值为射流速度的70%80%,高温射流与冷却水的临界流量比为0.91,且随井筒尺寸的增加而增大。高温射流破岩的能量利用率高,在深井硬地层中采用非接触式破岩可提高钻井速度。在实际较软地层钻井过程中,两侧冷却条件下的高温射流方案在需要进行扩眼钻进的地层具有一定的适用性。

英文摘要：

It is prone to encounter wellbore wall rock thermal spallation and collapse and drill string keeping in constant high temperature during hydrothermal jet drilling due to the returned high temperature fluid. To achieve safe and efficient drilling, the annular cooling scheme by side injecting cold water through drill pipe has been proposed. The effect of different jet velocities and temperatures and different cooling water velocities on annulus cooling perform-ance has been analyzed. Results indicate that, with the increase of the jet velocity, the average annular temperature is less sensitive to the change of the jet velocity, and has linear relation with the jet temperature. There exists a criti-cal cooling water velocity that makes the annular temperature distribution obviously different. The critical cooling wa-ter velocity is influenced by the jet velocity and the borehole diameter. When the cooling water velocity is higher than the critical value, it not only ensures the bottomhole rock breaking performance of the high temperature fluid, but also could effectively cool the annular. In the study,the critical value is 7 0 %？80% of the jet velocity,the critical flow ratio of the hydrothermal jet and the cooling water is 0. 91, and increases with the size of the wellbore. The en-ergy utilization rate of hydrothermal jet rock breaking is high, and the non-contact rock breaking in deep well hard layer can improve the drilling speed. In the soft formation drilling operation,the hydrothermal jet scheme under the cooling condition on both sides has certain applicability in the formation where reaming is needed.