钻柱抗弯强度分析

钻柱强度分析是钻具设计和选材的重要依据，对大中曲率水平并，抗弯强度是下部钻具强度分析中的首要问题．本文对弯曲并段内钻柱的抗弯强度进行了研究，给出了钻柱抗弯强度和极限转角的计算公式．提出了钻柱设计的极限转角准则：γｍａｘ＜β１／ｎｓ．文中计算了塞平－１井二开和三开段内所用钻铤的极限转角，并进行了抗弯强度校核，结果表明，所选钻柱满足强度要求．

Analysis of Well String Bending Strength

trength analysis is an important basis for drilling tools design and material selection. In the case of drilling horizontal wells having large or median curvature,bending strength of underneath drill string is one of the most important problems in strength analysis. In this paper,the bending strength of drill string in curved section of the well was investigated' The expressions of drill string bending strength and equations for computing the rotation limit were obtained. Based on these. a rotation limit criterion for drill string design is put forward: γmax<β1/n. As an example,the rotation limit of the drill collars used in the curved section of Saiping-1 Horizontal Well was calculated. Moreover, strength check was also made for the selected drill strings. The results show that the selected drill strings meet the strength requirements.