Production performance optimization of water-enhanced geothermal system based on effective time-averaged volume

Enhanced geothermal systems (EGS) hold great promise for geothermal energy extraction. However, accurately evaluating reservoirs and fractures remains a primary challenge in optimizing the production performance of EGS. This study addresses this gap by introducing a novel index, the effective time-averaged volume. It assesses the effectiveness of reservoirs and fractures, and system economy, making it a valuable tool for determining effective utilization times. Through establishing a triple-well fractured model, parametric studies are innovatively conducted. Results indicate that a reduced effective time-averaged volume leads to a higher thermal recovery rate and greater power generation. The optimized parameters of the model are a reservoir permeability of 0.5 mD, a primary fracture permeability of 50 D, an injection flow rate of 45 kg/s, an injection temperature of 20 °C, and a well spacing of 200 m. The cumulative power generation and effective time-averaged volume of the reservoir for 45 years are 4.89 × 10⁶ GJ and 4.78 × 10⁸ m³, respectively. Furthermore, we quantify the contributions of influencing factors to production performance, highlighting the significant impact of injection flow rate on system economy. These insights provide valuable guidance for the efficient design, operation, and optimization of EGS.