Creep Analysis Of Casing Under High-temperature And High-pressure

As the expansion of the zone and the depth of the petroleum well exploitation, high-temperature and high-pressure are the problems faced in many wells. They have caused great damage to the casing and need to be analyzed with special method.When analyzing the strength of casing in the high-temperature and high-pressure well, the effects of the creep of the casing as well as the non-uniform loading caused by the creep of wall rock are very important. On the basis of the previous research, this paper, from simple to complex, analyzed the creep properties of the casing with the elasticity, plasticity and creep theories.First,simplifying the mechanical model into a plane strain model, the analytic solutions of the effective stress and strain of casing under uniform loading were calculated. The results were helpful to estimate the longevity of the casing. And then the creep effect of the wall rock outside was taken into consideration too. Based on the double layer of casings'model, related solutions were worked out.Moreover, the mechanical model of the casing under non-uniform loading caused by rheological rock was set up, and then the asymptotic analytic solutions of the effective stress and effective strain were calculated. Compared with the result of the state with uniform loading in the examples, the non-uniform loading was proved to greatly reduce the strength and the longevity of the casing.At last, the effect of elastic deformation was taken into consideration and the control formations and the numerical computation method were provided.