The drilling fluid retention caused by casing eccentricity in horizontal well restricts the improvement of cementing quality and the advantage of horizontal well. To accurately describe the retention law and range of drilling fluid in horizontal well annulus, It was considered in the paper of the effect of driving force caused by density difference between slurry and drilling fluid in condition of casing eccentricity in horizontal well on extension of displacing interface. Based on the equilibrium condition of displacing interface stability, the boundary location calculation model on displacing interface of drilling fluid at casing and well in eccentric annulus was set up, and the effect of casing eccentricity on displacement in horizontal well was analyzed. The results showed that the displacement efficiency decreased and the thickness discontinuity of annular cement sheath increased as the increase of eccentricity when casing upper eccentricity, while the displacement efficiency increased and the thickness of annular cement sheath tended to be uniform at first and to be uneven as increase of eccentricity when casing lower eccentric. The casing lower eccentricity of 0.1 to 0.2 in horizontal well can bring about the best cementing quality, so the casing upper eccentric should be strictly controlled to prevent whole drilling fluid retention and uneven distribution of cement sheath thickness.%水平井套管偏心引起的钻井液局部滞留制约了水平井固井质量的提高和水平井优势的发挥,为了准确地描述水平井环空钻井液滞留的规律以及范围,考虑水平井套管偏心条件下水泥浆与钻井液密度差引起的驱动力对顶替界面扩展的影响,根据顶替界面达到稳定的平衡条件建立了水平井偏心环空套管和井壁处的钻井液滞留层边界位置计算模型,分析了套管偏心对水平井顶替效果的影响.研究得出:套管上偏心时随着偏心度的增加,顶替效率降低,环空水泥环的厚度分布不均程度增大；套管下偏心时顶替效率随着偏心度的增加而提高,环空水泥环的厚度先是趋于均匀而后逐渐变为非均匀；水平井套管下偏心偏心度控制为0.1～0.2能够获得较好的固井质量,应严格控制套管上偏心以防止整体钻井液窜槽和水泥环厚度分布不均现象的出现.
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