Simulation of Geothermal Energy Production Utilizing Abandoned Oil and Gas Wells

Abstract

Abandoned oil and gas wells (AOGWs) with suitable reservoir temperatures present a promising opportunity to convert subsurface heat into thermal energy or electricity for various applications. This study developed a rigorous thermodynamic model for a single-flash geothermal power plant utilizing a double-pipe direct heat exchanger (DHE), leveraging data from existing literature and modeling via Engineering Equation Solver (EES) software. The model simulates the system using R134a as the working fluid, assessing the influence of rock properties, geothermal gradient, DHE geometry, insulation thickness, mass flow rate of the working fluid, and alternative working fluids on heat extraction efficiency. This innovative approach allows for the efficient utilization of available geothermal heat resources, thereby enhancing the potential for sustainable energy generation. Key findings reveal that the power generation potential from AOGWs employing DHEs is significantly affected by the geothermal gradient within the well, the length of the heat exchanger, and the thermal conductivity of the surrounding rock. Additionally, the model projects the system's long-term performance over a 20-year period, emphasizing the importance of variable fluid characteristics inside the exchanger. Overall, the simulations underscore the necessity of carefully considering these factors to optimize energy extraction from AOGWs. The results highlight the feasibility of harnessing geothermal energy in low-flow-rate conditions, ultimately contributing to the sustainability of energy resources and offering insights for future developments in geothermal energy systems. This approach not only addresses environmental concerns associated with AOGWs but also positions them as viable assets for renewable energy generation.