充气控压钻井气液两相流流型研究

Research on aerated MPD gas and liquid two phase flow pattern

充气控压钻井是在充气欠平衡钻井技术的基础上发展起来的、针对具有窄安全密度窗口地层的一种钻井新技术。本研究将多相流体流动简化为气液两相流动,建立了充气控压钻井循环系统的物理模型,系统地总结和对比了气液两相流流型转换准则、压降计算模型,通过大量的模拟实验,验证、修正了常规气液两相流流型判别准则和压降模型,得出适用于充气钻井的压降计算模型。通过流型敏感因素分析,得出气液比、地面回压、流道的几何形状是流型主要影响因素,该研究结果为充气控压钻井的压力控制提供了理论依据。

Aerated Managed Pressure Drilling（MPD）is developed on the basis of aerated underbalanced drilling（UBD）. It is a drilling technology that mainly focuses on narrow safe density window formation. Through the study in this paper, the multiphase flow of the circulating system is simplified into gas and liquid two phase flow, a circulating system physical model of aerated MPD is established, and the transition criteria and pressure drop model of gas and liquid two phase flow are summed up systematically. Through a lot of simulating experiments, the transition criterion and pressure drop model of conventional gas and liquid two phase flow is verified and revised, the pressure drop model applicable to aerated MPD is developed. Through the analysis of flow pattern sensitive factors, gas and liquid ratio, ground back pressure, and flow geometry are major affecting factors affecting. The research result provides theoretical basis for pressure control of aerated MPD.