Analysis of some case studies and a recommended idea for geothermal energy production from retrofitted abandoned oil and gas wells

There are many oil and gas wells globally which are not used for production, injection or other purposes. By converting abandoned or non-activated oil and gas wells to geothermal wells, it would be possible to defer plug and abandonment costs and produce geothermal energy. As a crucial stage for the claim verification and evaluation of feasibility or efficiency of this conversion, it is important to be aware of the practical and simulation studies in the literature. Therefore, this work presents a comprehensive overview and analysis of 20 case studies published from different countries, followed by analysis of formations, important downhole and surface parameters. In terms of downhole, production scenarios either open-loop or closed-loop, optimization of open-loop systems, borehole heat exchangers with their different types and dimensions, insulations, positive hydraulic and thermal advantages of installing bottomhole curvature, are covered. Next, organic Rankine cycle (ORCs), selection of circulation fluids, circulation rates, and working fluids are covered, followed by the produced and net energies coefficient of performance (COP) and thermal efficiency. Finally, a recommended idea applicable to super-highly pressured aquifers is presented in an example case study. This investigation shows there is good potential for using geothermal energy from abandoned and old petroleum wells.