Geothermal energy recovery from abandoned petroleum wells: A review of the challenges and opportunities

[Display omitted] •Geothermal energy (GE) can deliver sustainable heat from petroleum wellbores.•GE technologies for heat recovery from abandoned petroleum wells evaluated.•Efficiency affected by depth, temperature, pressure, and working fluids properties.•Political/fiscal issues influence outlook for GE abandoned wellbore sector.•Mid/low temperature GE has economic and environmental challenges to overcome. The worldwide demand for fossil fuels, including oil, gas, and coal, has experienced a significant increase in recent years, despite the environmental pressures to reduce it. The escalating need for energy has resulted in heightened strain on fossil fuel and renewable energy resources, thereby posing challenges in consistently fulfilling energy requirements by sustainable means that mitigate environmental contamination, especially the release of greenhouse gases (GHGs). The aforementioned interconnected matters underscore the necessity for alternative energy solutions. Geothermal energy (GE) offers an attractive and viable renewable energy source with the potential to offer a substantial, sustainable energy supply while avoiding environmental degradation. This review comprehensively considers the technical, economic, and environmental aspects of GE recovery from abandoned petroleum wells (APWs). It focuses on the key technical factors, including wellbore integrity, heat recovery technologies, and the subsurface influences on deep wellbore heat extraction. It emphasizes optimizing energy recovery efficiency from individual APWs and entire abandoned petroleum fields, considering well depth and geothermal gradients. Practical considerations associated with heat exchangers, working fluids, thermal conductivity, corrosion, scaling, and remote operations are also reviewed. Challenges and opportunities associated with policy incentives, political motivation, regulations, environmental impacts, and economics are identified. Based on an assessment of current knowledge, recommendations are made for further research and field-testing requirements. The review provides a multi-dimensional understanding of the concept of repurposing APWs for GE recovery and the issues to be addressed to achieve that objective.