Purpose -This paper aims to develop a practical method to evaluate operational performance of workover rigs and present an approach to measure the overall equipment effectiveness (OEE) based on results of the evaluation method. Design/methodology/approach -The area of this study focuses on workover rigs processes in the oilfield and investigates the impact of workover activities on the production at the Sarir Oilfield in Libya. The loss of time from workover procedures and electrical submersible pumps ESP installation and pulling, which affect oil well production, should be eliminated in order to reduce the cost. Several example calculations of workover operation efficiency involving actual workover operational data are presented. The method of evaluation of workover process has been developing which were the bases of OEE calculation. Findings -The measure was developed to help support continuing efforts around process improvements and cost leadership at Oilfields. The results on the empirical findings are introducing OEE for the workover activities which will be used as a valuable indicator for workover activities improvement. Practical implications -The result of this research makes it possible to represent the OEE as a benchmark that will be used to compare the performance of workover process. Originality/value -This paper presents a successful and effective evaluation of OEE which will provide a useful observer to set of operational improvement areas and how such activities could be organised and managed more effectively.