中文摘要：

在套管柱设计中，套管外挤压力的计算十分重要。在《钻井手册（甲方）》中，蠕变性地层段的套管外挤压力取为上覆岩层压力，而S Y／T 5724-2008《套管柱结构与强度设计》中却将蠕变性地层段套管的外挤压力与岩石的泊松比联系起来，二者不相容。结合钻井施工过程的岩石力学理论，对蠕变性地层段的套管有效外挤压力进行分析。结果表明，SY／T 5724-2008《套管柱结构与强度设计》中关于蠕变性地层段的套管有效外挤压力的计算公式是错误的。建议采用《钻井手册（甲方）》中的蠕变性地层段的套管有效外挤压力计算公式进行套管柱结构设计。

英文摘要：

In the design of casing string ,the calculation of external pressure on casing is very impor-tant .In the Drilling Manual（Party A ） ,the overburden pressure of the formations is taken as the external pressure on casing in the creep formation section ,while the standards of The Structure and Strength of the Casing String Design（SY/T 5724 2008）sets the external pressure of casing as a function of rock Poisson’s ratio .Combining drilling process and rock mechanics theory ,the external pressure on casing in the creep formation section is analyzed .The result shows that the formula for effective external pressure on casing in creep formation section in the standards of The Structure and Strength of the Casing String Design（SY/T 5724 2008）is incorrect .It is recommended that the formula for effective external pressure on casing in creep formation section in Drilling Manual（Party A ）be used in casing design .