大斜度长水平井油管下入性力学分析

MECHANICAL ANALYSIS OF TUBING RUNNING IN HIGHLY DEVIATED LONG HORIZONTAL WELLS

大斜度长水平井眼中,水平井段的长度较一般井眼要长,随着油管与井壁的接触面积不断增大,摩擦阻力也逐渐增大,从而导致油管产生“自锁”现象,使得油管难以下入到预定井深,严重地限制了油气井的开发效率。针对这个问题,本文充分考虑井眼几何参数、油管几何参数、油管刚度以及屈曲问题,对不同屈曲状态下的油管进行受力分析,分别建立三种屈曲状态下油管的力学模型,采用安全系数法结合第四强度理论对油管的下入性进行研究。利用MATLAB分析软件,研究管径、摩擦系数与油管下入性的关系,研究结果表明27/8外加厚油管在摩擦系数为0.2时能够下入到指定井深。引用安全系数法并结合第四强度理论对油管的应力进行校核,数值计算结果与分析结果一致。

In high-angle long horizontal wells,the length of the horizontal well section is longer than that of ordinary wells.With the increasing contact area between the tubing and the sidewall,the friction resistance gradually increases,which leads to the“self-locking”phenomenon of the tubing,making it difficult to run the tubing into the predetermined well depth,which seriously limits the development efficiency of oil and gas wells.In order to solve this problem,this paper fully considers the geometric parameters of borehole,tubing stiffness and buckling,analyzes the stress of tubing in different buckling states,establishes the mechanical models of tubing in three buckling states,and studies the running-in performance of tubing by using the safety factor method combined with the fourth strength theory.Using MATLAB analysis software,the relationship between pipe diameter,friction coefficient and tubing running ability is studied.The results show that 27/8 outer thickened tubing can run to the specified well depth when the friction coefficient is 0.2.The stress of the oil pipe is checked by using the safety factor method combined with the fourth strength theory,and the numerical calculation results are consistent with the analysis results.