摘要
对陕北区域51/2″套管内开窗侧钻井所用的88.9 mm×CQST31加重钻杆出现外螺纹断裂事故进行分析。对其失效原因进行检查后发现该批加重钻杆外螺纹根部存在疲劳裂纹,因侧钻井起始井段狗腿度较大,钻进过程中,加重钻杆通过该井段,承受较大的交变弯曲载荷,外螺纹接头产生疲劳损伤;下放钻具时,加重钻杆发生屈曲,导致加重钻杆快速疲劳损伤而断裂。
The external thread fracture of 88.9 mm×CQST31 heavy weight drill pipe used for sidetracking in 51/2″casing in Northern Shaanxi was analyzed.After checking the failure causes,it is found that there is fatigue crack at the root of external thread of this batch of heavy weight drill pipes.The dogleg degree of the initial well section of side drilling is relatively large,therefore the heavy weight drill pipe passing through this well section bears a large alternating bending load during drilling,and the external thread joint is fatigued.Furthermore,when lowering the drill pipe,the heavy weight drill pipe buckles,resulting in rapid fatigue damage and fracture.
作者
孙等军
李培梅
张军
李勇
SUN Dengjun;LI Peimei;ZHANG Jun;LI Yong(CCDC Changqing General Drilling Company,Xi′an,Shaanxi 710018,China)
出处
《石油管材与仪器》
2020年第3期42-46,共5页
Petroleum Tubular Goods & Instruments
关键词
加重钻杆
断裂
疲劳损伤
heavy weight drill pipe
fracture
fatigue damage
