H_2S腐蚀下钻杆材料疲劳性能研究

Study on Fatigue Performance of Drill Pipe Material Under H_2S Corrosion

钻井工程中的钻杆除了长期承受轴向压力产生的疲劳损伤外,还承受着油气的腐蚀环境影响,油气开采往往大量伴生着H_2S的产生。采用旋转弯曲疲劳试验机对钻井中常用的S135材料进行疲劳试验,同时参照NACE TM0177—2005标准进行H_2S腐蚀实验,腐蚀时间分别为48 h和96 h,并对腐蚀后的试件进行疲劳试验,并分别得出了S-N曲线。用扫描电镜对疲劳破坏后的断口进行观察,得出了不同腐蚀时间下的疲劳断裂机理。腐蚀介质对试件表面粗糙度的影响占据了疲劳寿命影响的最主要的因素,且随着应力的降低表面粗糙度对疲劳寿命的分散性影响逐渐增大。

In drilling engineering,in addition to long-term bearing the fatigue damage caused by axial pressure,the drill pipe is also under the influence of oil and gas corrosion environment. Oil and gas production is often accompanied by a large number of H_2 S production. The rotating bending fatigue testing machine is used to carry out the fatigue test of S135 material which is commonly used in drilling,and the H_2 S corrosion test is carried out with reference to the TM0177- 2005 NACE standard,The corrosion time was 48 h and 96 h respectively,and the corrosion test specimens were fatigue test,the S-N curves were obtained. The fatigue fracture mechanism under different corrosion time was observed by scanning electron microscope. The experiments show that the influence of the corrosive medium on the surface roughness of the specimen is the most important factor that affects the fatigue life,and the influence of the surface roughness on the fatigue life is gradually increased with the decrease of the stress.