旋流扶正器作用下环空螺旋流场压降研究

PRESSURE DROP STUDY ON ANNULAR HELICAL FLOW FIELD UNDER ACTION OF CYCLONE CENTRALIZER

在油气井固井注水泥顶替技术中,使用旋流扶正器不仅可提高套管居中度,还能改变环空流体流速剖面,使流体做螺旋运动,螺旋顶替方式有利于将环空窄间隙滞留泥浆和井壁附着虚滤饼驱替干净,从而提高固井质量。液体螺旋流动方式改变了轴向流场压降的分布规律,展开螺旋流场压降的研究对注水泥安全施工有着重要意义。文章在实验的基础上,推导出了环空螺旋流场压降的计算公式,实验结果表明:环空螺旋流场的压降呈非线性衰减,且在同等条件下大于一维轴向流场的压降值,注水泥施工设计时应对其予以足够重视。

During the process of mud displacement by cementing, using the cyclone centralizer can not only improve the deviation of casings, but also change the flowing profile of the annular fluid to make the fluid helical movement. The helical displacement is favor to completely displace the residual mud in the narrow clearance of the annulus and the imaginary cake adhering in the bore wall, and improve the cementing quality. The helical flow of fluid changes the pressure drop distribution of the axial flow field. It is very important to study the pressure drop of the helical flow field for safe operation of cementing jobs. Based on the experiments, the formula is derived to calculate the pressure drop of the annular helical flow field. It is found by calculation the pressure drop of the annular helical flow field appears in the nonlinear attenuation and is bigger than the pressure drop of the one-dimension axial flow field under the same conditions, which should be sufficiently considered when designing the cementing jobs.