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固井注水泥顶替后,在套管壁和井壁上滞留的钻井液会严重危害固井质量。为对环空壁面上钻井液滞留层开展理论研究,将井眼环空看作由无数个变宽度的两平板组成。该文首先分析了注水泥顶替时环空间隙内流体切应力的分布特征,确定了壁面处钻井液产生滞留的条件,进而建立钻井液滞留层厚度计算模型,并采用“二分法”对模型进行了数值求解,计算了在不同套管偏心、井斜角及流体性质条件下钻井液滞留层在壁面上的厚度。并根据钻井液滞留层厚度计算模型,推导了环空壁面上不存在钻井液滞留时流体性质之间所需满足的定量条件。
After the cementing cement is replaced, the drilling fluid retained on the casing wall and the shaft wall will seriously damage the cementing quality. In order to conduct a theoretical study of the drilling fluid retention layer on the annulus wall, the wellbore annulus is considered to consist of numerous plates of variable width. In this paper, the distribution characteristics of fluid shear stress in the annulus when the cement injection was replaced by cement were analyzed, and the conditions for the retention of the drilling fluid at the wall were determined. Then the calculation model of the thickness of the fluid retention layer was established and the “dichotomy” The model was solved numerically, and the thickness of the drilling fluid retaining layer on the wall surface was calculated under different casing eccentricity, well inclination and fluid properties. According to the calculation model of the thickness of the drilling fluid retention layer, the quantitative conditions that are required to satisfy the fluid properties when the drilling fluid does not exist on the annular wall surface are deduced.