Hydrothermal evolution analysis and performance optimization in multi-well fractured reservoirs for enhanced geothermal systems

The successful development of Enhanced Geothermal Systems relies on constructing high-quality fracture networks. However, the mechanism of hydrothermal evolution in geothermal reservoirs with artificial fracture networks remains poorly understood. This study aims to elucidate the mechanism of hydrothermal evolution in fractured reservoirs to optimize geothermal energy extraction. Novel metrics, namely reservoir heating efficiency and reservoir flow efficiency, were introduced to assess performance. The study comparatively investigated six fracture structures and evaluated their impact on system production. Key findings reveal that fluid flow in multiple horizontal wells fractures reservoirs efficiently, with heat effectively extracted from the edges of the Stimulated Reservoir Volume. Enhanced reservoir heating efficiency and optimized flow efficiency were achieved due to improved heat exchange and fluid diversion. Optimal hydrothermal evolution was realized with a reservoir heating efficiency of 0.2022 and a reservoir flow efficiency of 0.2398, using a configuration of a 0° rotation angle, 30 kg/s injection mass flow, 60 °C injection temperature, 3.12 mm hydraulic fracture aperture, and 200 m production well spacing. These findings provide valuable insights into reservoir design and production strategies for Enhanced Geothermal System.