Abstract: The analytic formulae for computing the casing load and stress distribution in casing under non-uniform tectonic stress field are extended to the case that considers the internal pressure in the casing firstly. Then, the Tresca and Mises yield criterions are applied to deduce the computing formulae of collapsing pressure for casing destruction under the conditions of non-considering and with considering casing axial loads, respectively. By introducing the concept of the equivalent external extrusion pressure, the obtained formulae are the same with the formulae of API standard in format. The computation result shows that the risk of casing destruction will increase under the condition of nonuniform load.

Key words: non-uniform load, casing axial load, casing strength, collapsing pressure, yield criterion, computation formula, external extrusion pressure

摘要： 将非均匀地应力场中套管载荷和套管内应力分布的理论公式推广到包含内压的情况,并采用Tresca屈服准则和Mises屈服准则,分别推导了在忽略套管轴向载荷和考虑套管轴向载荷两种情况下套管强度破坏时挤毁压力的计算公式。引入等效外挤压力概念,使该公式与标准API公式在形式上完全一致。计算结果表明,在非均匀载荷情况下,套管强度破坏的危险性会增加。

关键词: 非均匀载荷, 套管轴向载荷, 套管强度, 挤毁压力, 屈服准则, 计算公式, 外挤压力