弹塑性范围内含体积缺陷连续油管安全评价

Safety evaluation of coiled tubing with volume defects within elastic-plastic range

含体积缺陷的连续油管在作业过程中可能发生卡断或拉断等事故,文章基于连续油管常见的缺陷形式,建立了含体积缺陷的连续油管模型,结合有限元基本理论,分析了塑性范围内的连续油管的剩余强度,以及不同载荷与缺陷尺寸特征对连续油管应力分布和极限承载能力的影响。分析结果表明:在塑性极限状态下连续油管的剩余强度要高于全弹性状态的剩余强度,连续油管的承载能力对缺陷深度和内压载荷表现的尤为敏感,随着缺陷深度的增加,承载能力变弱,并且在缺陷评价中应以压力载荷为标准。

The coiled tubing with volume defects may occur broken accidents during the operation. A coiled tubing model with volume defect was established based on the common defects of coiled tubing. Combined with the basic theory of finite element, the residual strength of coiled tubing within elastic-plastic range, and the influence of different loads and defect size characteristics on coiled tubing stress distribution and ultimate bearing capacity were analyzed. Analysis results show that, in plastic limit state, the residual strength of coiled tubing is higher than that of the whole elastic state. The carrying capacity of coiled tubing is very sensitive to the defect depth and the load of internal pressure. With the increase of the depth of the defect, the bearing capacity becomes weak, and the pressure load is the standard in the evaluation of the defects.