定向井环空内岩屑运移机理的研究

运用实验观察方法,对定向井环空内岩屑的运移情况进行了研究和分析。从宏观上看,斜井环空内岩屑的运移状况有四种不同的流动物理模型,即:均称悬浮流动、非均称悬浮流动、移动床流动和固定床流动。在不同斜度的井眼中分别存在一个对应的临界流速.从微观上分析,岩屑床床面的岩屑颗粒承受液流的拖曳力和上举力、粒间离散力、重力和浮力的作用。对于极细的岩屑颗粒,还承受粒间粘结力。研究结果表明,环空倾角对岩屑运移有一定的影响。倾角越大,越不利于岩屑的运移。液流流速越大,岩屑的运移越快。

TRANSPORT MECHANISM OF CUTTINGS IN ANNULUS OF DIRECTIONAL WELL

The transport mechanism of cuttings in annulus of a directional well was studied with visual observation.The cuttings transport can be macroscopically divided into four states,i.e.uniform,symmetric suspension movement,non-uniform,symmetric suspension movement,fluidized bed movement and fixed bed movement.There is a critical velocity in the wellbore,corresponding with its deviation angle.The forces particles of cuttings are drag force,lifting force,dispersion.gravity and buoyance.The finer particles are also subjected to inter-particle cohesive force.The results show that the movement of cuttings is affected by the deviation angle of the annulus.The greater the deviation angle the slower,the movement annulus,the faster the movement.