非均匀载荷下套管强度的计算

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。

Computation of casing strength under non-uniform load

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 ap- plied 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.