Paper: Solving Rod Buckling

Producing companies and operators are universally concerned with reducing failures in rod pumping systems. Costly failures effect a company's profitability. A leading cause of rod pumping failures is rod buckling. This paper discusses the problems, causes, and solutions of sucker rod buckling. Various methods of determining the buckling force are presented. These methods include computer modeling, physical downhole measurement, and empirical models. Furthermore, a calculation scheme is detailed for predicting buckling modes, patches. bending moments, and peak stresses in the rod string. Buckling hysteresis and friction are also discussed. The results of the buckling predictions are supported by actual stress measurements from a downhole load cell tool. Lastly, considerations for preventing severe rod buckling are offered. All material is presented for practical field application. .