Abstract Market demand for geothermal energy is rapidly escalating globally, largely due to the need for 24/7 electrification of power grids as well as policy changes toward decarbonization and GHG (greenhouse gas) reduction. The study aims to develop a streamlined workflow for evaluating the feasibility of repurposing late-phase or abandoned oil and gas sites for geothermal energy production and applies it to a case study in the southern United States. The workflow consists of three distinct phases: 1) Site Identification; 2) Feasibility; and 3) Economic Analysis. The analysis focuses on quantifying technical viability (e.g., reservoir temperatures, fracture networks) and economic metrics such as the Levelized Cost of Electricity (LCOE). The methodology includes assessing three heat extraction methods—Discrete Fracture Networks (DFN), Engineered Geothermal Systems (EGS), and Advanced Geothermal Systems (AGS)—by integrating geological, operational, and economic data. Case studies, selected for their distinct lithologies and heat flow conditions, provide a practical framework for comparing these methods and guiding infrastructure repurposing decisions. Leveraging detailed geological, geomechanical, and economic analyses, the study provides insights into reservoir capabilities, well construction requirements, and cost-effectiveness. Results of Dynamic Reservoir Modeling and sensitivity analyses revealed DFN systems as the most sustainable, achieving consistent energy production over a 30-year period under optimal fracture configurations. EGS scenarios exhibited variability in thermal output due to fracture density and cooling effects, with wider cluster spacing improving short-term efficiency but struggling with long-term thermal depletion. AGS systems, reliant solely on conductive heat transfer, demonstrated the lowest efficiency. Economically, DFN emerged as the most cost-effective (lowest LCOE), followed by EGS and AGS. The study concludes that repurposing oil/gas sites for geothermal energy is viable in regions with high heat flow (150°C) and natural fracture networks, with DFN-based systems offering the strongest technical and economic case for prioritization.
Pettitt et al. (Tue,) studied this question.