缺陷对连续油管极限承载能力影响分析

针对含有缺陷连续油管作业过程中极易发生卡断或拉断等事故,根据现场使用后的连续油管缺陷情况,把缺陷形状归为方形、球形和椭球形三种缺陷,并开展拉伸内压复合载荷工况下连续油管承载能力的研究。对比分析不同尺寸不同形状下含缺陷连续油管应力分布规律,在此基础上绘制轴向载荷(n=N/N_0)与内压载荷(p=P/P_0)包络线,通过现场数据直接判断连续油管是否在安全工作范围。通过有限元计算结果与API5C5标准计算结果验证有限元法的有效性和精确性。在此基础上开发含缺陷连续油管安全评估软件,获得不同型号不同缺陷形状情况下轴向载荷与内压载荷的包络线,为油田现场连续油管安全施工提供保障。

Analysis on the Influence of Defect on the Ultimate Load Carrying Capacity of the Coiled Tubing

Coiled tubing with surface defects prone to snap off or broken in the course of work. According to the coiled tubing defects after field service, the defect shape is divided into three kinds of defects, which are square, spherical and ellipsoidal. And study on the load carrying capacity of coiled tubing under tensile and internal pressure, and the stress distribution law of the defective coiled tubing was analyzed in different sizes under different sizes. On these basis, the axial load (n=N/N0) and the internal pressure (p=P/P0) envelope are plotted. Then directly determine whether the continuous coiled tubing is in the safe working range through field data. The validity and accuracy of the finite element method are verified by the results of finite element calculation and the results of the API5C5 standard. The software for safety assessment of coiled tubing defects is developed on the basis of the above, and the envelope line of the axial load and the internal pressure load was obtained in the different models of different types of defects, it can provide the guarantee for the safe construction of the coiled tubing in the field.