基于修正幂律模型流体的柳叶形扶正器旋流规律及应用

为提高注水泥过程中水泥浆顶替效率,国内外愈来愈多地使用旋流扶正器。但是,目前旋流扶正器结构参数主要靠经验设计,缺乏理论基础也没有相关行业标准。针对依据文丘里效应设计的柳叶形旋流扶正器,基于修正幂律流体模型,构建了旋流扶正器旋流长度计算模型。通过数值模拟对旋流扶正器井下旋流规律进行研究,推导出了旋流扶正器在修正幂律流体条件下,周向平均速度和完全顶替的临界速度公式。基于旋流扶正器井下旋流规律,分析了井眼环空结构、流体性能、井下井壁附着力对水泥浆顶替效率的影响,优化了柳叶形旋流扶正器旋流角、扶正棱长度、扶正棱有效体积和扶正器高度等设计参数。对比分析了柳叶形与常规旋流扶正器在不同工况下的旋流长度,柳叶形扶正器的旋流长度比常规扇形平均提升了32%,比常规梯形扶正器平均提升了47%。柳叶形扶正器在新疆顺北油田顺北3井等20多井次超深井应用,应用井固井质量明显优于常规扇形的旋流扶正器。

Swirling flow regularity of willow leaf-like centralizer based on modified power law fluid model and its application

To improve the slurry displacing efficiency during cementing, swirl centralizer is increasingly used at home and abroad. However, the structural parameters of current swirl centralizer are mainly designed by experience, lacking a theoretical basis and relevant industry standards. In view of the willow leaf-like swirl centralizer designed based on the Venture effect, a calculation model of the swirl flow length of swirl centralizer was established based on the modified power law fluid model. The regularity of downhole swirling flow in the use of swirl centralizer was studied by numerical simulation. On this basis, this study derives the formulas of critical speed of the circumferential average velocity and the complete displacement of swirl centralizer under the condition of of modified power law fluid. Based on the regularity of downhole swirling flow in the use of swirl centralizer, this paper analyzes the influence of borehole annulus structure, fluid performance and downhole side wall adhesion on slurry displacing efficiency, and optimizes the swirl angle, length and effective volume of casing centralizer, as well as the height and other design parameters of the willow leaf-like swirl centralizer. Through comparatively analyzing the swirl flow length of willow leaf-like and conventional swirl centralizers under different conditions, it has been found that the swirl flow length of willow leaf-like centralizer is 32% higher than that of conventional fan-shaped centralizer, and averagely 47% higher than that of conventional trapezoidal centralizer. The willow leaf-like centralizer has been applied in the well Shunbei-3 and other ultradeep wells in the Shunbei oilfield in Xinjiang for more than 20 well times, and the cementing quality is significantly better than that of the conventional fan-shaped swirl centralizer.