深水多梯度钻井空心球分离规律及其对井筒传热与传质的影响

深水注空心球多梯度钻井中井筒温度的准确预测对井筒压力控制有至关重要的作用。文章利用新的分离技术与室内实验相结合研究了空心球在不同影响因素下的分离规律。基于能量守恒方程、连续性方程以及动量方程并考虑分离效率对于空心球传质与传热过程的影响，建立了瞬态传热与传质条件下的温度与压力相耦合的井筒温度计算模型。并将现场测量数据与理论模型的计算结果进行对比，验证了文章所建模型的准确性。最后对影响环空温度以及热物性参数的重要因素如分离效率、空心球注入速率、分离器位置等进行了敏感性分析。研究表明，通过调节泵排量与空心球直径以及分离器位置，可以实现环空压力梯度的准确控制，很好地改善深水钻井中窄压力窗口引起的溢漏问题。

Separation Law of Hollow Spheres in Deepwater Multi-gradient Drilling and Its Influence on Wellbore Heat and Mass Transfer

Accurate prediction of wellbore temperature plays an important role during multi-gradient drilling in deep water. In this paper, the separation law of hollow glass spheres under different influence factors was studied by combining the new separation technology with laboratory experiments. Then, a transient wellbore temperature calculation model coupled with temperature and pressure was established, based on the energy conservation equation, continuity equation and momentum equation, and considering the effect of separation efficiency on the mass transfer and heat transfer process of the hollow glass spheres. The accuracy of the model was verified by comparing the field measurement data with the calculated results of the model. Finally, the sensitivity analysis of the important factors affecting the annulus temperature and thermos-physical parameters such as separation efficiency, injection rate of hollow glass spheres, separator location, etc has been performed. The study shows that the accurate control of annulus pressure gradient can be realized by adjusting pump rate, diameter of hollow glass sphere and position of separator, the well kick and lost circulation caused by narrow pressure window in deep water drilling can be well improved.