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文章在假设偏心环空为楔形区域的情况下，利用流体力学理论及幂律流体在楔形区域中的流动方程，分析了旋转套管及上下活动套管时水泥浆及泥浆在偏心环空中形成的流场，并研究了旋转套管及上下活动套管对效率的影响。结论认为注水泥旋转套管及上下活动套管都能使环空泥浆及水泥浆及泥浆处于剪切状态，并且旋转套管还能在环空宽间隙外侧形成回流。正是由于这种剪切与回流作用破坏了泥浆的胶凝结构，消除了环空窄间隙处的泥浆滞流，因而

THEORETICAL ANALYSIS OF MOVING CASINGS TO IMPROVE EFFICIENCY IN CEMENTING JOB

??An eccentric annulus is assumed as cuneiform area, and fluid mechanics and the flow equation for the power-law fluid in the cuneiform area are utilized for the analysis of flow field which is produced by mud and cement slurry while casings are being rotated and moved up and down.How the casing movement affects displacement efficiency is also studied.It is concluded that the fluid in an annulus is in shear state because of the casings movement.Back flows can be formed at the wide side clearance in an annulus with the casing rotating.For the destruction of mud gelatination structure by two actions of shear and back flow, the bypassed mud in the narrow clearance can be removed so that the displacement rate becomes higher than before.Calculation and analysis of the flow in the movement of casings in an annulus have shown that the shear and back flow actions are directly proportional to either the flow behavoir or the casing movement speed.So, it is beneficial to increase the displacement effciency by the destruction of mud gelatination structure and the removal of the bybassed mud.