扁化效应对弯曲段套管抗挤强度的影响对比分析  

Influence of Cross-Sectional Ovalization on the Collapse Strength of Curved Casing

作　　者：曹银萍[1] 窦益华[1] 李明飞[1] 索红娟 CAO Yinping;DOU Yihua;LI Mingfei;SUO Hongjuan(Mechanical Engineering College,Xi’an Shiyou University,Xi'an 710065,Shaanxi,China)

机构地区：[1]西安石油大学机械工程学院

出　　处：《力学季刊》2019年第4期780-787,共8页Chinese Quarterly of Mechanics

基　　金：陕西省自然科学基金(2019JM-473);国家自然科学基金(51674199)

摘　　要：针对弯曲段套管抗挤强度随井眼曲率变化规律问题,利用材料力学理论将弯曲段套管等价为均布载荷作用下的弯曲梁模型,根据拉梅厚壁筒理论和强度理论得到套管抗挤强度公式.借鉴扁化变形在圆管类结构中的研究思路,将其拓展到套管抗挤强度分析,对比分析是否考虑扁化效应下四种规格套管不同井眼曲率下的抗外挤强度.研究表明,套管轴向应力随井眼曲率基本呈线性变化;套管抗挤强度随井眼曲率的增加非线性下降.井眼曲率为2o/30 m时,是否考虑套管扁化变形得到的51/2"×10.54 mm P110套管抗挤强度误差为12.8%;井眼曲率为12o/30 m时,误差46.9%.井眼曲率为2o/30 m时,41/2"×9.65 mm TP140V套管抗挤强度误差11.9%;井眼曲率为12o/30 m时,误差44.7%.可见,考虑扁化变形后套管抗挤强度小于未考虑扁化变形情况;井眼曲率不大时,两种算法的差距较小,随着井眼曲率的增加,套管扁化变形对套管抗挤强度的影响不能忽略.To make clear the collapse strength of curved casing with wellbore curvature,the curved casing is taken as a bending beam under uniform load.The formula of collapse strength of curved casing is deduced using Lame theory and distortion energy theory.Taking the cross-sectional ovalization in circular tubes as reference,the formula for collapse strength of casing with cross-sectional ovalization is obtained.The collapse strengths with wellbore curvature for the four casings are compared between the methods with and without consideration of cross-sectional ovalization.It shows that the axial stress of casing changes almost linearly with the wellbore curvature.Collapse strength of casing decreases nonlinearly with increasing the wellbore curvature.For 51/2"×10.54 mm P110 casing,the difference between the two methods increases from 12.8%to 46.9%when wellbore curvature increases from 2 o/30 m to 12 o/30 m.For 41/2"×9.65 mm TP140 V casing,the difference between the two methods increases from 11.9%to 44.7%when wellbore curvature increases from 2 o/30 m to 12 o/30 m.In general,the collapse strength is smaller when considering the cross-sectional ovalization.The difference between the two methods is insignificant for small wellbore curvature.However,with the increase of wellbore curvature,the influence of cross-sectional ovalization on the collapse strength of curved casing cannot be neglected.

关 键 词：套管 抗挤强度 扁化 均布载荷 井眼曲率 

分 类 号：TE931[石油与天然气工程—石油机械设备]