Casing collapse is major problem of the oil fields which causes increase of costs to oil companies. This problem can be seen not only at drilling time in some formations but also after the completion and production may cause problems. exact prediction of collapse pressure is a very important factor in the casing design. Casing Collapse generaliy is a function of the geomechanical properties of the formation and the properties of the solid mechanics of the casing. One of the properties of solid mechanics that affects the testing of the collapse can be the ovality of the casing and the difference in the thickness of the casing and the existence of residual stress during the construction of the casing. In this paper, using numerical methods, the effect of each of the above-mentioned solid mechanics parameters and formation creep on the collapse of the casing has been investigated. The results of this study indicate that pipe defects, such as casing ovality, eccentricity and the presence of residual stress, reduce the strength of the casing.

This reduces the resistance to the extent that the casing at the time of installation due to high plastic strain will collapse and also it was found that the pipe imperfections is more effective than rock salt creep in casing collapse.