考虑非牛顿流体螺旋流动的钻井井筒温度场研究

摘要

Understanding wellbore temperature and its changing regularity is very critical for drilling safely and efficiently .According to the first law of thermodynamics and heat transfer theory ,a complete temperature field mathematical model for drilling circulation was established .The heat transfer mechanism in spiral flow of non-New tonian fluid in wellbore and the effect of hydraulic energy and mechanical energy on wellbore temperature field were analyzed .A preliminary discussion was conducted regarding calculation of ECD under high temperature and high pressure and control over wellbore temperature .The model re-sults matched well with field experimental data .Numerical simulation indicated bottomhole temperature in-creased by 4.5 ℃ at the depth of 2 000 m ,and 7.8 ℃ at 5 000 m respectively w hen the rotary speed of drillstring rose from 0 r/min to 200 r/min .The bottomhole temperature increased exponentially with the increase of rotary speed ,the drill string rotary speed had much higher effects on bottomhole temperature with the increase of well depth .This model can provide a theoretical reference for hydraulic design of drill-ing in HT HP formation and temperature control during field operations .%准确了解钻井过程中井筒温度及其变化规律对于安全、高效钻井具有重要的意义。根据热力学第一定律及传热理论，建立了完整的钻井循环过程中温度场数学模型，分析了井筒中非牛顿流体螺旋流动的传热机理以及水力学能量和机械能量对井筒温度场的影响规律，对高温高压循环当量密度计算和井筒温度控制方法进行了初步探讨。模型计算结果与现场试验数据吻合较好。由数值模拟结果得出：在井深2000.00 m处，钻柱转速从0 r/min升至200 r/min时该处温度升高4.5℃；在井深5000.00 m处，钻柱转速从0 r/min升至200 r/min时该处温度升高7.8℃。研究结果表明，井底温度随钻柱转速的增加呈指数增长，随着井深的增加，钻柱旋转对井底温度的影响更加明显。建立的温度场模型可为高温高压地层钻井水力学设计和现场作业过程中的温度控制提供理论参考。