充气欠平衡钻井环空气液固三相流动力学分析

DYNAMICS ANALYSIS OF ANNULAR GAS-LIQUID-SOLID THREE PHASE FLOW IN AERATING UNDERBALANCED DRILLING

近年来,充气欠平衡钻井由于其容易实现,井筒压力调节范围大,可控制地层出水,利于井壁稳定等优点,国内外应用日渐增多。但是,充气欠平衡钻井是一门很复杂的技术,最关键的问题在于环空气液固流动是一个复杂、变化很快的动态过程,关于气液固三相流的动力学特征,迄今研究甚少。文章根据多相流体力学原理,对环空气液固三相流动力学特性进行分析,结果表明:除重力和颗粒间的相互作用力外,固相颗粒主要受到由压差阻力,摩擦阻力,视质量力,Basset加速度力,压强梯度力,马格努斯力和滑移-剪切升力组成。认识到充气钻井液在环空中的段塞流动和假液化特性对井眼净化是有利的,细小颗粒的假液化速度比粗颗粒大。

In recent years, the aerating drilling technology is widely applied at home and abroad for the technique has larger wellbore pressure adjustment range, can controlling the formation water and keep wall steady. But the technology is complex, and the gas-liquid-solid flow in the annular is a process of complex and changing fast. In this paper, based on the multiphase fluid mechanics theory, the dynamics features of the gas-liquid-solid flow were researched. The research results indicate that the forces of solid phase grain mainly are the pressure difference resistance, friction resistance, apparent mass force, Basset acceleration force, pressure gradient force and velocity gradient force besides the interaction force between gravity and grain. The slug flow and pseudo liquefy of aerating drilling fluid in the annular is benefit for hole cleaning. And the velocity of pseudo liquefying for the small grain is larger than the lager grain.