三种套管接头抗压缩性能研究

针对套管接头抗压缩强度问题，使用全尺寸实物试验的方法对几种不同钢级、不同螺纹形式的套管接头的抗压缩强度进行了对比试验，并借助材料力学和有限元方法对试验结果进行了分析。实物试验中出现了管体失稳和接箍跳扣两种套管接头压缩失效形式。试验结果和分析结果表明，N80、P110钢级材料的压缩屈服强度高于拉伸屈服强度；偏梯形螺纹套管接头的压缩屈服强度比同钢级、同壁厚特殊扣螺纹套管接头低6.7%～7.7%；上扣是否到位，直接影响套管接头部分的抗压缩能力，上扣不到位的特殊螺纹套管接头的抗压缩性能甚至低于偏梯形螺纹接头。同时指出，为了保证上扣质量，不应使用浮动上扣方法，管柱设计中应进行抗压缩强度设计。

STUDY ON COMPRESSIBILITY OF 3 KINDS OF CASING JOINTS

Aiming at the compressibility of casing joints, using full-size real objects of casing joints with different steel grades and thread profiles, their compressibility is compared by testing. Based on the material mechanics and the finite element method, the testing results are analyzed. Two modalities of casing joint failures i.e. pipe body buckling and joint jumping happen in the testing. The testing and analyzing results show the compression yield strength of the steel grades of N80 and P110 are greater than the tension yield strength. The compression yield strength of the casing joint with eccentric trapezoidal thread is 6.7%~7.7% lower than that of the casing joint with special thread under the conditions of same steel grade and wall thickness. The make-up quality of casing joints will directly influence the compressibility. The compressibility of the casing joints with special thread and poor make-up quality is even lower than that of the casing joints with eccentric trapezoidal thread. To guarantee the make-up quality, the float making-up method should not be used. The casing-string design should consider the compression strength of joints.