管内转向径向水平井携岩规律数值模拟

Numerical Simulation of the Cuttings-Carrying Law in Radial Horizontal Well

为了对管内转向径向水平井携岩规律进行研究,根据流体力学理论建立了管内转向径向水平井携岩过程的数学模型和物理模型,采用数值模拟方法研究了流量、钻速和井径等参数取不同值时,环空截面混合流体速度分布规律和岩屑体积分数分布规律。分析结果表明,随着流量的增大,混合流体紊流强度增强,悬浮层内岩屑体积分数增大,固定床层内岩屑体积分数减小,岩屑床总高度降低,偏心环空内高速流核区范围增大;随着井径的扩大,岩屑在偏心环空上的非均匀性增强,偏心环空底部岩屑床高度增加,偏心环空中高速流核区减小,零速度区范围逐渐增大,混合流体平均流速减小。

To study the law of carrying cuttings in in-casing steering radial horizontal wells, the mathematical and physical models of the cuttings-carrying process in the wells were established according to hydrodynamic theo- ry. The numerical simulation method was used to study the distribution laws of mixed fluid velocity in annular sec- tion and cuttings volume fraction when different values were taken with regard to such parameters as flowrate, drill- ing rate and borehole diameter. The analysis shows that, with the increase of flowrate, the turbulence intensity of mixed fluid increases, the cuttings volume fraction increases within the suspension layer and decreases within the fixed bed layer, the overall height of the cuttings bed decreases, and the scope of the high speed flow core zone within the eccentric annulus increases ; with the increase of borehole diameter, the unevenness of cuttings in eccen- tric annulus increases, the height of the cuttings bed at the bottom of eccentric annulus increases, the high speed flow core zone reduces within eccentric annulus, the scope of zero speed gradually increases and the average flow- rate of mixed fluid decreases.