Optimization of Well Workover Efficiency: A Case Study of Cost-Effective Adoption of Hydraulic Workover Unit Technology

Abstract This study explores the strategic adoption of Hydraulic Workover Unit (HWU) technology by two leading indigenous energy firms in Nigeria. The objective was to achieve significant cost efficiencies while adhering to the highest safety protocols during well workover operations. The initiative began with collaborative brainstorming sessions to explore innovative methodologies beyond traditional rig operations. A thorough examination of rig-based activities and infrastructure identified opportunities for operational optimization and cost efficiency. The HWU emerged as a promising alternative, despite inherent challenges. Comprehensive risk and uncertainty mitigation analyses were conducted, leading to the development of a robust and safe HWU work module. The inaugural deployment of the HWU on a shallow offshore well's initial completion was successful and incident-free. Encouraged by this success, the HWU operation was replicated in land locations, converting two oil wells to water injection wells through workover operations. The initial completion of the shallow offshore well achieved an impressive production rate of over 4,000 barrels per day and a 40% cost saving compared to traditional rig operations. The onshore conversions were executed within six weeks per well, at a cost of $4.5 to $6.0 million each, significantly lower than the conventional rig costs of $8 to $12 million. These successful cases demonstrate the effectiveness of adopting HWU for workover operations across diverse environments (land and shallow offshore). This paper details the processes and methodologies employed, offering valuable insights into a potential avenue for cost reduction exceeding 50% for typical workover operations in the Nigerian context.