深井大直径井段的钻井问题研究

A STUDY ON DRILLING PROBLEMS OF DEEP LARGE DIAMETER WELLBORES

随着我国深井数量的增加，深井上部大直径井段钻井速度慢的问题日益突出。在系统分析了大直径井段中普遍存在的钻井问题的基础上，指出当前深井大直径钻井技术的根本问题，是钻具、钻头、钻井装备与大直径井眼的工艺要求不相适应。在软地层中主要表现为：沿程水力损失很大，水功率利用率极低，导致井底比水功率很低，井底和钻头清洗不良，影响机械钻速。在硬地层和砾石层中主要表现为：钻压不足，导致机械破岩能量明显不足，同时大尺寸钻头齿面结构设计不合理，破岩效率低。文中提出了解决深井大直径钻井问题的具体措施，对提高深井钻井速度具有一定的指导意义。

Problems commonly presented in deep large diameter wellbore drilling have been analyzed systematically in this paper. It ispointed out that the essential drilling problem is the unsuitability of the drill pipe,drill collar,drill bit and drilling equipment forthe needs of deep large diameter wellbore drilling. In soft formations,the main problems are the large hydraulic losses,low hydraulic horsepower,and poor bit cleaning conditions. In hard formations and gravel beds,the main problems are insufficient bitweight,unreasonable design of cutting structures of drill bits,and low rock breakage efficiency. To solve the problems,a series oftechnical steps are suggested in this paper.