侧向载荷作用下的套管塑性破坏力学模型与计算分析

Mechanical Model and Computational Analysis of Casing Plastic Failure Underlateral Loadng

首次针对套管柱承受屈服页岩横向载荷展开研究,运用虚功原理建立了一个横向载荷均匀分布页岩剖面上的力学模型,得出在套管柱径向变形阶段,其横向承载强度迅速下降;对于轴向变形,其横向承载强度变化不大。本文通过计算实例,为优选套管方案提供了可靠的分析工具,增强屈服粘土层段套管柱承受横向载荷的能力,减小套管失效率,降低油田操作费用。

The resistance of casing string against the lateral loads from the yielding shales is discussed. According to the principle of virtual work, the mechanical model is established which indicates that the lateral loads are evenly distributed on the shale sections, and the resistance of casing string to the lateral loads drops sharply in the stage of development of radial deformation. The resistance of casing string to the lateral loads is not very sensitive to the longitudinal deformation. The remaining strength of casing string also depends on properties of the casing string. This work provides an analytical tool to optimize casing programs against lateral loads from yielding clay zones to minimize casing failure and field operation cost.