弯曲井段内连续油管稳定问题的存在性分析

基于弹性杆大位移-小变形理论，利用微分方程法，给出了弯曲井段内连续管柱失稳临界载荷的解析结果，并讨论了弯曲井段内，连续管柱存在稳定问题的条件。研究表明，弯曲井段内临界载荷不仅与连续管柱几何特性参数相关，还与井眼直径和曲率有关。井眼直径和曲率半径越小，临界载荷越大，其他条件一定，井眼曲率半径减小到一定程度时，临界载荷超过强度极限载荷，管柱稳定问题转化为强度问题。

Existence Analysis of Coiled Tubing Stability in the Crooked Section in Horizontal Well

An analytic stability result of the CT in the crooked section of horizontal well is obtained with the differential equation analysis and the large displacement/small-strain theory of an elastic rod. The conditions of CT buckling in the crooked section are discussed and the possibility of buckling is demonstrated in theory. The results show that the critical load in the crooked section is not only associated with the characteristic parameter of CT, but also with the diameter and curvature of well. The less diameter and curvature of well are,the more critical load is. And that when the curvature of the crooked section increases to a definite value,the problem of CT stability will be transferred into its strength problem as the value of critical load is more than the limit intensity load.