Φ31.8mm连续油管断裂失效分析

Fracture Failure Analysis of Φ31.8 mm Coiled Tubing

为了预防和减少连续油管在油田作业环境下发生的失效事故,提高连续油管的使用寿命,通过理化性能检验、微观组织分析和能谱分析等方法,对某油田80钢级Φ31.8 mm×3.18 mm断裂失效连续油管进行了分析。结果表明,该连续油管在受到自重产生的拉应力、周期性的塑性应变和井内酸性腐蚀环境的共同作用下,发生应力腐蚀开裂,导致连续油管断裂失效。最后给出了提高连续油管使用寿命的建议。

In order to prevent and reduce the failure accidents of coiled tubing in oil field operation environment, increase the service life of coiled tubing, the fractured coiled tubing of 80 steel grade Φ31.8 mm ×3.18 mm in a certain oilfield was analyzed through physical and chemical properties testing, microstructure analysis and EDS analysis. The results showed that the stress corrosion fracture occurred in this coiled tubing under the combined action, including tensile stress by its own weight, cyclic plastic strain and the well acidic corrosive environments, which caused the fracture failure for coiled tubing.Finally, some advices were put forward to increase service life of coiled tubing.