基于Hele-shaw模型的斜井偏心环空顶替流体密度差优化

针对斜井中顶替流体密度差及套管偏心引起的顶替界面突进两相流体掺混严重的问题,考虑斜井密度差引起的驱动力沿周向角和半径的变化,建立了斜井偏心环空稳定顶替界面形状模型,利用该模型分析了密度差对顶替界面形状的影响,得到了不同井斜角及套管偏心条件下顶替流体的最优密度差及变化规律:斜井中顶替界面突进的位置及程度取决于套管偏心与密度差的相对作用,存在合理的密度差使得顶替界面长度最短;最优顶替流体密度差随套管偏心度的增加而增大,随井斜角的增大而减小;固井顶替时在满足压稳防漏的条件下直井所选用的密度差越大越好,水平井所选用的密度差应相对最小。

The Optimization of Density Difference in the Eccentric Annulus of Inclined Well on the Basis of Hele-Shaw Model

To research into the problems of two-phase fluids intermixing and slurry's fingering caused by density difference and casing eccentricity in the inclined well,the modified mathematical model for steady displacement interface shape in the eccentric well is established in this paper which consider the driving force generated by density difference that changes with the circumferential angle and borejiole radius.The optimal density difference corresponding to different inclination angle and casing's eccentricity is obtained by using the modified model to analyze the effect of density difference on the displacement interface shape.The results show:the position and extend of slurry fingering depend on the relative effect of casing's eccentricity and density difference.There exists a optimal density difference that can make the interface length minimum.Besides,the optimal density difference increases with the increase of casing's eccentricity and decreases with the increase of inclination angle.Therefore,greater density difference can obtain better displacement effect for the vertical well when meeting the conditions of pressure stability and anti-leak.Otherwise,smaller density difference can get better displacement effect for the horizontal well.