Innovative Workflows for Brown Field Revitalization - Case Study from Libya

Abstract Over the years, hundreds of oil wells in the largest oil field in Libya have been depleted, leaving considerable oil volumes behind due to strong aquifer support and improper water encroachment management. A comprehensive intervention program was developed to evaluate and produce this trapped oil. Conventional electric submersible pump (ESP) designs did not consider changes in hydrocarbon saturation. Therefore, tailored Y-tool systems were used to achieve inflow profile passes and avoid undesired nonproductive rig time. The intervention workflow involved a thorough review of the workover histories of nearly 100 wells, revealing prevalent well integrity issues and solids production. Many wells experienced a gradual decline in oil production rates, leading to frequent ESP failures. To tackle these challenges, a comprehensive workover program was devised. This program involved retrieving failed pumps, assessing wellbore integrity, installing ESP bypass systems, and conducting casedhole logging for saturation monitoring and flow profiling. Multirate and pressure transient tests were performed to accurately assess reservoir performance, informing subsequent remedial actions. This integrated approach enabled dynamic reservoir evaluation, facilitating the identification of bypassed and remaining hydrocarbons, damaged areas, watered-out zones, and well integrity issues. The comprehensive evaluation provided insights crucial for the accurate design of ESP systems tailored to each well's potential. This level of precision, previously unattainable due to the absence of measurements of the dynamic reservoir conditions, underscores the significance of the integrated methodology in optimizing well performance and mitigating ESP failures. Through the implementation of this approach, over 100 previously shut-in and underperforming wells were effectively restored. These efforts resulted in a remarkable surge in oil production, with a gain of nearly 63,000 barrels of oil per day (BOPD), coupled with a substantial reduction in water production exceeding 90,000 barrels of water per day. These outcomes validated the effectiveness of the project and led the operator to embark on a subsequent phase. This next step seeks to capitalize on the success of the initial endeavor and embrace further opportunities for progress and advancement.