斜直井中扭矩和轴力共同作用下钻柱的屈曲问题

BULKING LOAD OF DRILL PIPE UNDER TORQUE AND AXIAL FORCE IN SLANT HOLE

利用能量方法研究了轴向载荷和扭矩共同作用下钻柱的屈曲问题 ,着重研究了扭矩对钻柱屈曲的影响 ,理论分析和实验验证均发现 ,轴向载荷、井斜角和扭矩是影响钻柱屈曲的重要因素。当其他条件相同时 ,钻柱的屈曲载荷随井斜角的增加而增加 ,呈非线性 ;扭矩使钻柱的屈曲载荷明显降低 ,并且随井斜角的增大 ,降低的幅度减小 ;扭矩值越大 ,钻柱的刚度越小 ,钻柱屈曲载荷的降低程度就越显著。

The energy method is employed to study the bulking load of drill pipes under torque and axial force in slant hole. The emphasis is placed upon the influence of torque on the bulking load. A large amount of experiments are carried out to verify the theoretical analysis. The experimental results and theoretical calculation are in satisfactory accordance. The axial load, well inclination angle and torque are the dominating factors that influence the bulking of drill pipes. When other conditions keep unchangable, the bulking load of drill pipes increases nonlinearly with the well inclination angle. However, torque can reduce the bulking load of drill pipes greatly, and the degree of reduction goes down with increase of well inclination angle. The greater the torque and the stiffness of the drill pipe are, the more obvious the reduction of bulking load resulted from the torque will be. The conclusions can be referred to practical applications.