WS1井?88.9mm四方钻杆断裂原因分析

ANALYSIS ON ?88.9MM SQUARE KELLY BREAK IN WELL WS1

吕拴录 王新虎

Lu Shuanlu Wang Xinhu

中国石油天然气集团公司管材研究所, 陕西西安 710065

Tube Research Inst. of CNPC

WS1井发生了一起88.9mm四方钻杆断裂事故,造成了很大的经济损失。为搞清事故原因,对四方钻杆断裂事故进行了研究。采用宏观分析方法和扫描电镜微观分析方法对四方钻杆断口宏观形貌和微观形貌进行了观察分析,认为四方钻杆断裂具有疲劳断裂的特征;采用直读光谱仪、力学性能试验设备和金相显微镜对断裂四方钻杆材料化学成分、机械性能和金相组织进行了试验分析,发现四方钻杆材料强度和韧性不足。调查研究和试验分析结果表明,四方钻杆断裂位置处于结构突变位置,断裂属于早期疲劳裂纹引起的脆性断裂失效,失效原因主要是材料质量不合格和机加工质量差所致。该研究对于防止同类事故再次发生,有着重要的借鉴意义。

The accident of ?88.9 mm square kelly break in well WS1 caused great economic losses, and a study was conducted to probe the causes of this accident. Macro analyzing method, as well as micro method of using scanning electron microscope was applied to identify and analyze the kelly break-fracture, and the features of fatigue failure were identified. Test analysis was also carried out to determine the chemical composition, mechanical property and metallographic structure of the kelly, and it was concluded that the material strength and toughness is not sufficient enough. Study and test results showed that the break took place at the structure mutation location, and it was of brittle failure due to earlier fatigue fractures, and the main causes of kelly break were unqualified raw material and poor machining quality. This study can be used as a reference to prevent the happening of such accidents in the future.

10.3969/j.issn.1000-7393.2004.05.010