Repurposing Hydrocarbon Wells: A Geothermal Assessment and Filtering Framework

Abstract The conversion of abandoned petroleum wells into geothermal wells presents a sustainable opportunity to repurpose idle infrastructure while advancing clean energy solutions. Abandoned wells, if left unaddressed, can pose significant environmental hazards, including methane emissions, groundwater contamination, and land subsidence, making their conversion to geothermal wells both a necessity and an opportunity for sustainable energy development. This study focuses on the Long Beach area, where approximately 4,900 wells exist, of which around 400 are classified as idle. Using data collected from the West Wilmington Oil Field and the Long Beach Unit THUMS, a detailed analysis was conducted on 22 selected wells, including those near the Long Beach port and residential areas. These 22 wells were strategically chosen to ensure comprehensive coverage of both port facilities and significant residential zones, allowing for a thorough evaluation of conversion feasibility in diverse land-use settings. The methodology involved grouping wells based on similarities in wellbore design and downhole equipment. From these groupings, four generalized well layouts were developed, incorporating details such as well depths, casing configurations, cementing practices, and other completion characteristics. Well trajectories, such as Build-and-Hold and S-type, are commonly considered for geothermal conversion, as they are prevalent among the selected wells. These trajectories are particularly advantageous due to their extended lateral sections and optimal inclination angles, which enhance heat extraction efficiency. Inclined boreholes, typical in these well paths, can also reduce total borehole length while maintaining effective geothermal energy output. The conversion capabilities of each well layout were assessed to determine the most suitable geothermal conversion method based on structural feasibility. This study establishes a framework for filtering idle petroleum wells that can be converted into geothermal wells based on the studied wells’ characteristics. This study aims to address legacy environmental challenges and contribute to the transition toward renewable energy systems while also reducing capital costs associated with geothermal system development by leveraging existing infrastructure. The findings provide a foundation for optimizing well conversion strategies and advancing sustainable energy initiatives in Long Beach and other hydrocarbon basins worldwide.