Paper: Critical Evaluation of Sucker Rod String Design Procedures

A properly designed sucker-rod string should provide failure-free pumping operations for an extended period. According to its prime importance in sucker-rod pumping technology several design procedures based on different assumptions were developed in the past. Correct description of rod loading conditions during the pumping cycle led to the inclusion of fatigue endurance limits into rod string designs and discusses their main characteristics; design results are compared for example cases. The paper also provides a more thorough comparison of designs involving the calculation of loads and stressed predicted from the solution of the damped wave equation. Using a predictive analysis program rod stresses are calculated that, plotted on the modified Goodman diagram, provide a proper comparison of merits of the different rod string design methods.