Numerical Investigations of Factors Affecting the Heat Energy Productivity of Geothermal Wells Converted from Hydrocarbon Well Pairs

Repurposing end-of-life hydrocarbon wells for geothermal energy generation offers a cost-effective and sustainable strategy to expand low-carbon energy deployment while utilizing existing infrastructure. Fracture-connected horizontal oil and gas well pairs present a promising configuration for enhancing heat transfer in low-permeability reservoirs. Existing modeling approaches, however, lack the ability to simulate transient heat conduction from rock to fluid in such complex fracture pathways. This work develops a mathematical model that couples time-dependent heat conduction in the reservoir rock with convective heat transport within the fractures. This model enables prediction of heat energy productivity of converted well pairs by accounting for realistic boundary conditions and operational parameters. In applying the model to a representative shale gas field in Louisiana, key factors affecting fluid temperature and thermal power output, including fracture geometry, fluid flow rate, and wellbore insulation, were considered. The results demonstrate the feasibility and sensitivity of converting hydrocarbon wells into geothermal energy production, providing critical insight for optimizing such conversions to support the increased demand for clean, sustainable energy.