TY - JOUR TI - Numerical simulation on downhole flow and temperature fields during drilling with nitrogen jet AU - Cai Chengzheng AU - Ren Keda AU - Liu Jiangfeng AU - Liu Shuang JN - Thermal Science PY - 2019 VL - 23 IS - 13 SP - 711 EP - 717 PT - Article AB - In petroleum engineering, nitrogen drilling is an important technology for building wellbores between surfaces and reservoirs. To uncover the downhole flow field and the change rules of rock temperature during drilling with nitrogen jet, we constructed a CFD model by coupling the property equations of nitrogen. The flow fields of nitrogen jet and rock temperature distribution at different times were simulated. Results showed that the high speed nitrogen jet can be efficiently generated because of the nozzle acceleration and the impingement effect can be induced during drilling. The temperature of the nitrogen jet decreased due to the Joule-Thomson effect. This phenomenon suggested that the nitrogen jet induced additional thermal cracks on the bottomhole rock, which was very beneficial for the improvement of rock-breaking efficiency.