Effects of creep of the salt rock formation on the failure of cement sheath integrity

Abstract

Salt rock has a good sealing ability for oil and gas, but the creep of salt rock may cause wellbore integrity failure, and even cause safety accidents and economic losses in serious cases. Based on the creep law of salt rock obtained from the creep experiment of salt rock, the finite element model of casing-cement sheath-formation combination in salt rock formation is established. The effect of formation creep on the integrity of cement sheath under different uniform in-situ stress conditions is studied. The results show that the creep of salt rock will cause the shear failure of the cement sheath; reducing the elastic modulus of the cement sheath and increasing the Poisson's ratio of cement sheath will reduce the risk of shear failure of the cement sheath.