连续油管的力学行为研究

MECHANICAL PERFORMANCE RESEEARCH ON COILED TUBING

连续油管以其不同于常规钻杆和油管的材质、作业工艺与装备,有着不可替代的优势,使其在钻井、采油等应用领域得到了飞速发展,与连续油管作业工艺相关的力学问题的研究也在迅速跟进。连续油管向滚筒上缠绕的过程属于弹塑性的拉弯大变形问题,通过虚功形式的动力学普遍方程,得到将连续油管缠绕于滚筒时需要施加在滚筒上的扭矩和驱动液马达的输出功率,发现作用在滚筒上的扭矩与连续油管所受的轴向拉力之间近似呈线性关系。利用弹塑性理论分析了缠绕在滚筒上的连续油管在卸除拉力和弯矩后的力学行为,证明了连续油管在弹塑性卸载过程中不会发生反向屈曲,而且拉力的作用有助于减小回弹,卸载回弹后连续油管的曲率半径随着拉力的增大而单调下降。因此连续油管缠绕上滚筒后一直要保持弯矩,以避免回弹乱管。

Coiled tubing (CT), because of the materials which are different from conventional drilling pipe and tube, its operation technique and the facilities, is unique, and fast development of CT has taken place in drilling and production. Meanwhile, the mechanical researche on operating process of CT are also following quickly. Studies on CT, when it is wrapped on the reel, belongs to the area of large elastic-plastic stretch bending deformation. By means of general equation of dynamics in the form of virtual work, the torsion torque needed by the reel to wrap CT and the actual output power of hydraulic motor can be derived out. It's found that the torsion torque exerted on the reel is almost linear to the axial stretch of the CT. Mechanical behaviors of CT are analyzed by elastic plastic theory when the CT is wrapped on the reel and then unloaded. It is demonstrated that reversed buckling will not happen. After unloading and resiling, the curvature radius of CT decreases monotonously along with stretch increasing. As a result, stretch is helpful to reducing resilience. It is suggested that the bending moment should also be remained in order to avoid CT resiling and disastrous mess after the CT is wrapped on the reel.