弯曲套管抗挤强度有限元ANSYS分析方法

Finite element ANSYS analysis method of bending casing collapsing strength

蒋官澄 胡冬亮 许发宾

中国石油大学石油工程学院，山东  东营  257061 胜利油田有限公司纯梁采油厂，山东  东营  257000

College of PetroleumEngineering, China University of Petroleum, Dongying 257061, China Chunliang Oil Production Plant,Shengli Oilfield Company, SINOPEC, Dongying 257000, China

针对我国各油田套变井数量上升，工程参数计算复杂的情况，通过建立ANSYS有限元模型，研究了4种常用套管尺寸的抗挤强度与套管弯曲率的关系，提出了使用有限元编程方法，快捷、高效计算在不同套管弯曲率条件下，套管抗挤强度、最大应力的方法，对指导套变井防砂、套管修复及常规油井酸化、压裂等工程作业具有重要的指导意义。弯曲套管最大应力随井眼曲率的增大而增大，最大应力点在弯曲的外侧。同一井眼曲率下，外径越大的套管相应点应力值越大。套管弯曲率增加，抗挤强度下降。弯曲率超过40 °·hm-1以后，抗挤强度下降变缓。

Aiming at the increase of casing deformation wells in each oilfields and the difficulty of handy calculation of engineering parameters, this paper analyses the relations between collapsing strength and bending ratio of four sizes of commonly used casing by finite element model in ANSYS, then proposes a method of finite element method programming to calculate casing strength of collapse resistance and maximum stress of different bending ratios, which is of important guiding significance for sands control or casing repair of casing deformation wells, and acidification or acid-fracturing of conventional wells. The maximum stress of bending
casing increases as borehole curvature increases and maximum stress point is in the lateral side. At the same borehole curvature, the larger the outer diameter is, the larger the stress of corresponding point will be. As borehole curvature increases, collapsing strength decreases. While borehole curvature exceeds, collapsing strength decrease slows down.