摘要
为了深入研究环空涡动时的流场特性,根据流体力学理论,以连续性方程和N-S方程为控制方程,利用计算流体力学技术对钻柱涡动时环空赫巴流体的流动进行了系统的数值模拟,研究了不同公转方向下钻柱偏心度的变化对环空切向速度剖面与合速度剖面的影响。通过对模拟数据的对比分析,发现不同公转方向下环空流场分布截然不同,正向公转时切向速度在环空宽间隙处随着公转速度、自转速度和偏心度增大正向增大;反向公转时会出现二次流,切向速度在环空宽间隙处随偏心度的减小整体反向减小,同时二次流趋势越明显,摩阻压耗越大。合理应用这些规律有助于完善现有钻井水力学理论,更好地揭示井下环空流场特性,并为钻井水力参数优化设计提供有效的理论指导。
To further understand features of flow field during vortex in annulus, impacts of eccentricity variations on tangential velocity profile and resultant velocity profile of annulus under different rotation directions were determined according to the fluid dynamics theories and with continuity equation and N-S equation as controlling equations. In this study, systematic numerical simulations were performed on flows of Hershel-Bulkley fluid in annulus during vortex of drill pipes by using fluid dynamics. Through comparison of simulation data, it is seen that distributions of flow fields in the annulus are significantly different in different rotation directions. During rotation in positive direction, tangential velocity increases with the increases of revolution speed, speed of autorotation and eccentricity around wide clearance of annulus. During rotation in negative position, secondary flows are observed, and tangential velocity decreases reversely with the decreases of eccentricity in wide clearance of the annulus. Moreover, more obvious the trends of secondary flows, higher the frictional pressure losses. Proper application of these patterns may improve existing hydraulic theories for drilling operations to highlight properties of flow fields in the annulus and to provide theoretical guidance for design and optimization of hydraulic parameters for drilling operations.
出处
《石油钻采工艺》
CAS
CSCD
北大核心
2016年第2期133-137,共5页
Oil Drilling & Production Technology
基金
国家重点基础研究发展计划(973计划)"深井复杂地层安全高效钻井基础研究"(编号:2010CB226704)
关键词
涡动
环空
赫巴流体
摩阻压耗
数值模拟
流场
vortex
annulus
Hershel-Bulkley fluid
frictional pressure loss
numerical simulation
flow field
