抽油光杆低温脆断机理及合金化增韧研究

Study on Low Temperature Brittle Fracture Mechanism and Alloying Toughness of Polished Rod

针对胜利油田东胜公司CO_(2)驱油生产中受效油井出现的抽油光杆低温脆裂问题,采用电火花元素分析、金相分析、夏比冲击实验等方法,开展了抽油光杆脆断机理研究,重点分析了合金成分和微观结构对抽油光杆冲击韧性的影响。结果表明,抽油光杆的韧脆转变温度在-40~-20℃之间,正好处于液态CO_(2)注采工况下的温度敏感区间,导致脆断发生。通过添加Ni、Ti、N等合金元素、表面淬火及形变强化等方法对抽油光杆进行合金化增韧,改进后抽油光杆的微观组织发生明显变化,韧脆转变温度降至-60℃左右,低温冲击韧性显著提高,满足了液态CO_(2)驱油生产需求。

Aiming at the low-temperature fracture of polished rods in the effective oil wells of Dongsheng company of Shengli oilfield,using EDM element analysis,metallographic analysis,Charpy impact test and other methods.The brittle fracture mechanism of polished rods has been studied.The effects of alloy composition and microstructure on the impact toughness of polished rods were analyzed.The results show that the ductile-brittle transition temperature of ordinary smooth sucker rods is between-40℃and-20℃,which is just in the temperature sensitive range under liquid CO2 injection and production conditions,leading to brittle fracture.Through deformation strengthening,adding Ni,Ti,N and other alloy elements to toughen polished rods,the micro morphology of improved polished rods are changed significantly,the ductile-brittle transition temperature is dropped to about-60℃,and the low-temperature impact toughness is significantly improved,which can meet the demand for low-temperature liquid CO2 enhanced oil recovery production.