连续油管钻水平井岩屑运移规律数值模拟

Numerical Simulation on Cuttings Carrying Regularity for Horizontal Wells Drilled with Coiled Tubing

连续油管钻水平井过程中,井底岩屑在重力作用下容易沉积在井壁下侧,形成岩屑床;连续油管又受到排量小、钻柱无法旋转等因素限制,造成井眼净化效率较低。针对这一问题,在欧拉坐标系下考虑相间滑移速度和颗粒流的影响,建立了微小井眼水平井岩屑运移的混合物漂移模型,采用Realizeκ-ε湍流模式及SIMPLEC算法进行数值计算,研究了钻井液排量、环空偏心度、岩屑直径、井斜角和钻井液黏度等参数对偏心环空岩屑运移的影响,得到了各种条件下环空岩屑速度和浓度的分布规律。研究表明:随着钻井液排量增大、环空偏心度减小、岩屑直径减小、井斜角减小及钻井液黏度提高,连续油管水平井岩屑运移效率提高。

During the course of drilling horizontal well with coiled tubing ,cuttings easily settle on the low side of borehole to form cuttings bed due to action of gravity .The features in the coiled tubing drilling , such as small pumping rate and no rotation in drill string etc ,have made hole cleaning efficiency very low . In view of this problem ,considering the interphase slip velocity and particle flow influence based on the Eu-lerian coordinate system ,a mixture drift model of cuttings carrying in a horizontal slim-hole was estab-lished ,w hich uses Realize κεturbulence model and the SIM PLEC algorithm for numerical calculation ,and studied the effects on eccentric annular cuttings migration by flow rate ,annular eccentricity ,cuttings size , mud viscosity and hole angle ,to determine distribution pattern of cuttings velocity and concentration in an-nular space under all conditions .The study shows that cuttings carrying efficiency will increase in coiled tubing drilling horizontal wells with the change of several factors ,i .e .the increase of flow rate of drilling fluid ,the decrease of annular eccentricity ,decrease of cuttings size and well inclination ,and the increase of mud viscosity .