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

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