水平定向钻管道穿越孔底泥浆的力学特性

Hole-bottom slurry mechanical properties of horizontal directional drilling in pipeline crossing project

将水平定向钻(HDD)回拖过程中孔底泥浆的流动假定为幂律流体在同心环形空间中的稳定流动,考虑内管轴向运动对流场分布的影响,根据Navier-Stokes方程推导泥浆压力梯度与管道外表面泥浆剪切应力的解析计算方法。基于搜集的HDD工程实例采用该解析方法进行数据分析,并与现有Baroid经验公式、SPE经验公式和Polak经验公式的计算结果进行对比。结果表明:由解析方法求得的泥浆压力梯度与实测值相差最小;泥浆拖曳阻力是回拖载荷的重要组成部分,计算中不可忽略;扩径比是泥浆压力梯度与剪切应力计算中敏感性最强的因素。

Provided that the flow of hole-bottom slurry(HBS)is a power-law fluid and flowing stably in concentric annulus space during the towback of horizontal directional drilling(HDD)operation and taking the influence of axial motion of inner pipe on flow field distribution into account,the analytic calculation method(ACM) about slurry pressure gradient and slurry shear stress at pipe outer surface are deduced based on the Navier-Stokes equation. Based on the HDD engineering examples, the data are analyzed by this method, and compared with the results of Baroid,SPE and Polak empirical formula,and ACM results are closest to the measured values. The slurry drag resistance is important part of the towback load and thus cannot be ignored in calculation. The expanding diameter ratio is the most sensitive factor in slurry pressure gradient and slurry shear stress at pipe outer surface in calculation.