套管弯曲强度与极限转角研究

以弹塑性理论和极限分析理论为基础，对弯曲井段内套管的抗弯强度进行了研究，给出了套管强度和极限转角的计算公式．分析表明，套管的Ⅰ级极限转角βⅠ可作为套管选材的依据，并由此提出了套管设计的极限转角准则：Ｙｍａｘ＜βⅠ．结合长庆油田塞平—１水平井固井工艺设计，对多种套管的极限转角进行了实例计算，并采用极限转角准则，对其弯曲井段内的技术套管和油层套管进行了选材，为套管串结构设计提供了理论依据．还对所选套管进行了弯曲强度校核

Investigation on Bend Strength and Bend Limitation Corner of Casings

The bend strength of casings at curved well segment was investigated based on the theory of plasto elasticity and limitation analysis in this paper.The formules of the bend strength and bend limitation corner of casings were obtained.It is show that the first bend limitation corner β 1 can be considered as the basis on which the casing material is chosen,whereby the bend limitation criterion of casing design is put forward as Y max <β 1.By combining with the cementing technology of Saiping 1 horizontal well in Changqing Oil Field,limitation corners of various casings were calculated.And by using the criterion of limitation corner,the material of technical casings and casings used in oil layers were chosen,which provides theoretical basis for the structure design of casing string.Morever the bend strength of the casing chosen was checked.