Abstract: The production casing stress inside steam-injection wellsis analyzed with a casing temperature field. Thecommercial software, ANSYS, is used to simulate the casing stress underdifferent conditions, and the results indicate that the highest thermalstress is at the internal wall, exceeding the elastic yield ultimate stress ofN80 casing, while the maximum thermal expansion occurs in thetemperature-transition area. In case that the surrounding area of casings isemptied, the thermal strain will be much higher than the elastic strain limit,and should be mainly responsible for the deformation failure of casings.Based on the results, some preventive measures for casing deformation areproposed, which are verified through the application of TP120TH casingsduring the well completion in Liao'he oilfield.