抽油杆疲劳性能实验分析

Experimental Analysis of Sucker Rod’s Fatigue Performance

目的有效地预防和减少因抽油杆断裂导致的油井修井作业,进一步降低油田开发成本。方法采用岛津电液伺服疲劳试验机,对D级和H级抽油杆进行材质成分分析,测试力学性能、空气和腐蚀介质下疲劳强度、拉压载荷对疲劳性能的影响,并进行对比分析。结果H级抽油杆的力学性能优于D级抽油杆。随着含水量的增加,两种抽油杆的抗疲劳性能均降低,在空气中,H级抽油杆的疲劳性能均优于D级抽油杆。在腐蚀环境中,D级抽油杆的疲劳性能优于H级抽油杆,并且两种抽油杆所受拉压载荷对疲劳均有一定影响。结论含水是影响抽油杆腐蚀疲劳性能的关键因素,H级抽油杆应在低含水区块应用,D级抽油杆在中高含水区块应用。抽油杆中和点以下产生的附加拉应力是导致抽油杆偏磨的直接原因,在中和点以下应优化扶正防磨设计。在中高含水区块,应加大对服役年限较长抽油杆的更换力度,以减少和预防抽油杆断裂事故的发生。

Objective To effectively prevent and reduce the workover of oil wells caused by sucker rod breakage, and further reduce the cost of oil field development. Methods In this paper, Shimadzu electro-hydraulic servo fatigue testing machine was used to analyze the material composition of sucker rods of classes D and H, and the mechanical properties, fatigue strength under air and corrosive media, and the effect of tensile and compressive loads on fatigue performance were tested for comparison and analysis. Results The mechanical performance of Class H rods was better than that of Class D rods. The fatigue resistance of both rods decreased with the increase of water content. In the air, the fatigue performance of Class H rods was Superior to that of Class H sucker rods;in the corrosive environment, Class D sucker rods had better fatigue performance than Class H rods.The tension and compression load of both sucker rods had certain influences on fatigue. Conclusion Water content is a key factor that influences the corrosion fatigue performance of sucker rods. Class H sucker rods should be applied in low-water-bearing blocks. Class D sucker rods should be used in mid-high water-cut blocks. The additional pulling stress produced below the neutral point of sucker rods is a direct cause of eccentric wear of sucker rods. The design of righting and anti-wear should be optimized below the neutral point;in mid-high water cut areas, the replacement of sucker rods with longer service life should be used to reduce and prevent fracture of sucker rods.