Comprehensive Model for Effect of Dual String Interaction on Buckling in Vertical Wells

Drill string buckling has always been an important subject in a well completion design. Oil wells typically have multiple concentric casing strings. In common practice the outer string is assumed to be rigid, while in reality the outer string can displace when induced by contact force of inner buckled pipe. Interaction between dual strings has significant influence on buckling behavior. Better understanding of dual string buckling behavior helps to give reliable reference for completion design. An analytical mathematical model has been brought up to describe the post buckling behavior of dual string. The newly derived model has been verified with previous literature. Effect of contact interaction has been considered in this model and evaluated in analysis. Case study has been conducted to further explore the buckling mechanism of dual string system. The influence of different parameters on final buckling configuration has been investigated.