南海东部大位移井岩屑床动态运移与参数优化

Dynamic Transportation and Parameter Optimization of Cuttings Bed in Extended Reach Wells in the East of South China Sea

井眼净化是南海东部大位移井钻井过程中关键的问题之一,而全井筒岩屑床的动态模拟对提高井眼净化效果有重要意义。鉴于此,在两层动态岩屑床运移模型的基础上,结合扩散方程完善了上下两层质量交换的计算方法,模拟了全井筒岩屑床的动态分布。结合岩屑床破坏器对扩散系数的影响,模拟了不同岩屑床个数和间距对井眼净化的影响,并对连续循环系统的使用效果进行了评价。研究结果表明:岩屑在井筒中呈波浪式分布;随着岩屑床破坏器数量的增加,井眼净化效果越好;但是当岩屑床破坏器数量大于6个时,继续增加数量对井眼净化效果的影响不大,建议岩屑床破坏器放置的个数为6个;随着岩屑床破坏器间距的增加,井眼净化效果减弱,建议岩屑床破坏器放置的间隔为9根钻杆。研究结果可为大位移井井眼净化作业提供技术支持。

Hole cleaning is one of the key issues in the drilling of extended reach wells in the east of the South China Sea,and the dynamic simulation of cuttings bed in the whole wellbore is of great significance to improve the effect of hole cleaning.Based on the two-layer dynamic cuttings bed transportation model and the diffusion equation,the calculation method of mass exchange between the upper and lower layers was improved,and the dynamic distribution of cuttings bed in the whole wellbore was simulated.In consideration of the impact of cuttings bed remover on the diffusion coefficient,the influence of the number and spacing of cuttings beds on hole cleaning was simulated,and the application effect of continuous circulation system(CCS)was evaluated.The results show that cuttings are distributed in waves along the wellbore.With the increase of the number of cuttings bed removers,the hole cleaning effect gets better.However,when the cuttings bed remover is more than 6,further increase in the number of cuttings bed has little effect on the hole cleaning effect.Therefore,it is recommended to place 6 cuttings bed removers.On the other hand,as the spacing of cuttings bed removers increases,hole cleaning effect declines.So,it is recommended to place cutting bed removers at a spacing of 9 drill pipes.The study results provide technical references for hole cleaning of extended reach well.