新型快速上扣套管螺纹的设计与应用

Design and application of a new type of fast make-up casing thread

基于海上钻井作业特殊工况的要求,设计了新型快速上扣套管螺纹,新型螺纹锥度为1∶12,螺距为6.35 mm,导向面为30°,承载面为0°,并且采用台肩结构进行位置约束,采用内平设计避免紊流。有限元力学分析结果表明,新型螺纹的等效应力分布均匀,连接强度高于管体本身;室内全尺寸实物试验结果表明,新型螺纹具有良好的上卸扣特性,无粘扣现象,具有较高的连接强度,密封性能好。新型快速上扣套管螺纹在渤海某油田的现场应用效果良好,下套管过程快速、平顺,没有发生错扣现象,上扣速度比同规格API偏梯形螺纹提高20%以上,大大提高了下套管作业效率。

Based on the requirements of special work condition in offshore drilling operation,the new type of fast make-up casing thread is designed with 1∶12 conicity,6.35 mm thread pitch,30° guiding face and 0° supporting face.The shoulder structure is adopted to constrain the position,and internal flush is designed to avoid the turbulent flow.The finite element dynamics analysis indicates the new thread presents uniform equivalent stress distribution and higher joint strength than the casing.The laboratory full scale test shows that the new thread is characterized by good making-up and breaking out,no thread gluing,high strength of joint and well sealing property.The new thread has made well application effect in an oilfield in Bohai Sea,with fast and smooth making-up,no cross threaded,and make-up speed raised by 20% compared with API buttress thread,so that the operating efficiency of casing job is improved greatly.