西北油田钻杆腐蚀疲劳敏感性模拟研究

Study on the Corrosion Fatigue Sensitivity of Drill Pipe in Northwest Oilfield

为明确西北油田钻杆在服役中的腐蚀疲劳风险,主要通过模拟钻杆服役工况的旋转弯曲腐蚀疲劳试验,并结合有限元软件模拟,研究了当钻杆表面存在不同缺陷深度时,钻杆的腐蚀疲劳敏感性的规律。结果表明:在模拟实际钻杆服役工况条件下,当钻杆试样存在腐蚀缺陷深度为0.2 mm、孔径为1 mm的腐蚀圆孔时,钻杆发生腐蚀疲劳风险已显著增加;当只考虑钻杆弯曲载荷对钻杆在实际工况条件下腐蚀疲劳的影响,如钻杆表面缺陷为内部平滑、均匀过渡的椭球型缺陷,对于31/2钻杆,当钻杆表面缺陷对应的应力集中系数为1.36时,钻杆在实际工况条件下腐蚀疲劳寿命会大幅度降低,对应的深径比为0.17~0.18。

For clarifying the corrosion fatigue risk of drill pipe in service in Northwest Oilfield,the corrosion fatigue sensitivity of drill pipe was studied when there were defects with different depths on the surface of drill pipe by simulating the rotary bending corrosion fatigue test of drill pipe working condition with the finite element software simulation.Results showed that the risk of corrosion fatigue of drill pipe increased significantly when there was corrosion round holes with a depth of 0.2 mm and a diameter of 1 mm under the simulated actual working condition of drill pipe.With only considering the influence of bending load of drill pipe on the corrosion fatigue of drill pipe under the actual working condition,which assumed that the surface defect of drill pipe was an ellipsoidal defect with smooth and uniform internal transition,when the stress concentration coefficient corresponding to the surface defect of 31/2 drill pipe was 1.36,the corrosion fatigue life would be greatly reduced under the actual working condition,and the corresponding depth diameter ratio was 0.17~0.18.