Heat Extraction Optimization of Well Clusters for Hydrothermal Reservoir Development

In recent years, hydrothermal geothermal resources have been predominantly exploited through well cluster systems, achieving extensive commercial implementation. The efficient development of such systems remains critically dependent on the comprehensive characterization of regional geological conditions, as multiple subsurface parameters—including stratal thickness, structural relief, porosity–permeability distribution, and fault architecture—exert substantial control over reservoir performance. However, the effective integration of these geological factors to optimize well network configurations, balancing economic viability, power output, and other evaluation metrics to enhance heat extraction efficiency and delay thermal breakthrough, remains unresolved. This study aimed to identify the optimal well cluster for hydrothermal geothermal resources in the X region. Geological, drilling, and well-logging data were compiled to construct a region-specific geological model. A coupled numerical model of fluid flow and heat transfer was developed for a five-spot well pattern. System performances under two commonly applied injection-to-production ratios (2:3 and 1:4) and spatial configurations between injection and production wells were quantified. A multi-criteria evaluation framework integrating heat extraction power, injection–production pressure difference, and production temperature decline was implemented to holistically assess well cluster. An integrated weighting strategy combining subjective expertise and objective analytical criteria was implemented alongside the TOPSIS method to systematically identify the optimal wellfield configuration. Results demonstrate that Pattern 11, comprising three injection wells and two production wells, achieved superior comprehensive performance among 15 patterns, with heat extraction power 24.13 MW, and production temperature decline <1 °C and injection–production pressure difference <3 MPa.