钻柱振动条件下的钻井液冲蚀引起的钻柱失效*

钻柱失效问题已经成为高压喷射钻井技术发展和推广的瓶颈。建立了一种钻柱失效的新理论模型,利用振动的知识研究钻柱的失效情况,分析钻柱在振动条件下的位移和速度,在此基础上利用冲蚀理论对钻柱的失效进行研究,分析得出钻井液对钻柱的冲蚀磨损量和最大冲蚀角。根据算例计算与分析,对应算例参数进行室内实验和井场实验设计,完成实验的验证与结果分析。结果表明:在考虑钻柱振动条件下,钻井液对钻柱的冲蚀磨损量要远大于未考虑钻柱振动条件下钻井液对钻柱的冲蚀磨损量;同时得知最大冲蚀角与冲蚀理论中的规定是完全吻合的以及钻井液对钻柱冲蚀所发生的最大角度在钻柱有无振动的条件下是相同的。研究结论对于在石油钻井中如何减少钻柱的失效及如何提高钻柱的使用寿命具有一定的理论参考意义。

Drill string failure caused by drilling fluid erosion under the condition of drill string vibration

Drill string failure has become the bottleneck of development and promotion of high-pressure jet drilling technology. In this paper, a new theoretical model of drill string failure is established. Using the vibration knowledge, the drill string failure is studied and the displacement and velocity are analyzed under the condition of vibration. On this base, we use the erosion theory to study and analyze the drill string failure, and then gain the erosion masses and maximum erosion angle of drill string by drilling fluid. According to the numerical example calculation and analysis, the numerical example parameters are designed by the laboratory experiment and well field experiment, and the experimental verification and results analysis are completed. The results show that: considering the drill string vibration, the erosion masses of the drill string by drilling fluid are much greater than that not considered. Meanwhile, the maximum erosion angle is proven to be in good agreement with the erosion theory requirement and the maximum angle produced when the drilling fluid erodes the drill string is the same whether the drill string vibration exists or not. The study conclusions have a certain theory reference significance to how to reduce the failure of drill string and how to improve the service life in oil drilling.