按地应力确定套管外挤压力的探讨

Determining external extrusion force on casing by terrestrial stress

以井眼周围的受力分析为基础，推导出考虑地应力时的套管外挤压力计算式，以及运用声波法确定地应力有关参数的表达式。对江汉油田周12井井下套管的实例计算表明，考虑地应力时的套管外挤压力大于常规按上覆岩层压力计算的外挤压力，因此认为，按常规方法设计的套管柱强度偏低，按地应力设计的套管柱强度才更符合实际。

Based on an analysis of the force around the borehole, the equation for calculating the external extrusion force on the casing is derived in considerahon of the temetrial stress, and the expression for determining the parameters related to the terrestrial stress is worked out by using the sound wave method. An exarmple of calculation shows the external extrusion force calculated by the above-mentioned equation is larger than that calculated by the conventional method, therefore the casing string should be designed in consideration of the terrestrial stress to meet the strength requirement.