THE STRENGTH ANALYSES OF DUAL CASING STRING FORCED IN HOMOGENEOUS AND INHOMOGENEOUS STRESS

The elasticoplastic finite element simulation analyses nave been made for the dual casing strings by EPT software.The analyses results are identical with M.Brkowsky’s testing results in German Technology University.The relative error of casing collapsing strength is about 0 to 3.8 Percent.When dual casing strings forced in homogeneous stress,the casing inner diameter displacement simulated by EPT is very close to the exact solution,so that elasticoplastic finite element model,basic assumes,and the elasticoplastic of increasement theory presented in this paper have been proven.The simulating test of casing strings forced in stress can replace the real test process and decrease the expeniment equipment and the problems in real test.The EPT software has been successfully used in Huabei oil field to determine the casing strings and establish the models of change of radial displacement as well as strength analyses.