Study on Strength Reduction of Casing with Surface Defects

The three-dimensional finite element model is built up by ANSYS according the J55 casing actual dimensions calculating the wearing casing maximum Mises stress imitating the original crustal—stress in the deep stratum conditions.The maximum Mises stress of uniform and non-uniform abrasion are obtained in different wearing lengths and depths.The calculating results show the wearing casings maximum Mises stress has an exponential increased relationship with the wearing length under the fixed wearing depth.For uniform wearing,the maximum Mises stress of casing exponentially increases as the wearing depth decreases;the maximum Mises stress of non-uniform abrasion has a direct linear ratio relationship with the wearing depth.The function of calculating the wearing casing maximum Mises stress is obtained from the numeral results under Mises failure criterions.Our methods and results can serve as a reference in calculating the strength of wearing casing.