CML双梯度钻井瞬态井筒温压耦合场

Transient Wellbore Temperature-Pressure Coupling Field in CML Dual Gradient Drilling

针对CML双梯度钻井井筒温压耦合场的相关研究较少。为此,基于CML双梯度钻井的工艺特点,考虑井筒内钻井液的流动特点以及温度、压力对钻井液物性参数的综合影响,建立了井筒温压耦合场数学模型,并结合钻井数据进行了数值计算和敏感性分析。计算及分析结果表明:返回管线与海水之间为单管横掠式传热,受到周围环境温度的影响较大,其温度分布与海水温度分布类似,井筒温度对钻井液密度的影响要大于压力的影响;在CML钻井中,通过动态调节钻井液帽的高度可以灵活控制井筒压力;通过对钻井液帽高度、泵压、排量进行优化设计,可以更好地满足对目标井底压力的控制需求。所得结论可以为深入研究CML双梯度钻井的控压钻井工艺设计提供理论参考。

The wellbore temperature-pressure coupling field in CML dual gradient drilling has been rarely studied.In this paper,based on the characteristics of CML dual gradient drilling technology,as well as the characteristics of drilling fluid flow in the wellbore and the comprehensive influence of temperature and pressure on the physical parameters of the drilling fluid,a mathematical model of wellbore temperature-pressure coupling field was built.Then,combined with drilling data,numerical calculation and sensitivity analysis were conducted.The calculation and analysis results show that the heat transfer between the return pipeline and the seawater is a single pipe cross swept heat transfer,which is greatly affected by the ambient temperature,the temperature distribution is similar to that of sea water,and the influence of wellbore temperature on the drilling fluid density is greater than that of pressure.In CML drilling,the wellbore pressure can be flexibly controlled by dynamically adjusting the height of the drilling fluid cap.Through optimization of drilling fluid cap height,pump pressure and displacement,the control requirements for the target bottomhole pressure can be better met.The conclusions provide a theoretical reference for the in-depth study and managed pressure technological design of CML dual gradient drilling.