Regional-Scale Development Assessment of Heterogeneous Geothermal Reservoirs: Digital Reconstruction of Parameter Maps, Spatially Constrained Zoning, and Coupled Groundwater Flow and Heat Transport Simulation

For regions with limited geothermal geological data, regional reservoir parameters are often difficult to directly incorporate into numerical models, while the linkage between heterogeneous zoning and detailed simulations remains insufficient and full-domain multi-scenario modeling requires substantial preprocessing effort. Taking the medium-to-deep hydrothermal geothermal reservoir in Anguang Town, Da’an City, Jilin Province, China, as the study area, this study proposes a regional geothermal development assessment framework integrating the digital reconstruction of parameter maps, finite-element parameter mapping, spatially constrained K-means clustering, and three-dimensional coupled groundwater flow and heat transport simulation. Regional reservoir parameter fields were reconstructed from published geological contour maps through georeferencing, contour vectorization, and continuous parameter-field reconstruction, and were subsequently mapped onto a three-dimensional FEFLOW finite-element mesh. Spatial cross-validation showed that the R2 values for all predicted parameters exceeded 0.99 and the NRMSE values were below 2.18%, indicating that the reconstructed parameter fields reliably preserved the spatial variations represented by the original maps. Based on total reservoir thickness, hydraulic conductivity, porosity, and initial temperature, a spatially constrained K-means algorithm was then applied to delineate the study area. Comparison of different values of K and spatial constraint coefficients identified five hydrothermal zones, and the influence of parameter weighting on the zoning results was further evaluated. Representative locations from different zones were subsequently selected for constant-drawdown pumping tests and typical production–reinjection simulations. The results show that differences in development response among the zones are primarily controlled by regional hydrothermal conditions. At a drawdown of 100 m, pumping rates at typical representative locations ranged from 1255 to 3369 m3/d, while the 50-year cold-front propagation distances ranged from 348 to 674 m. Zones with higher hydraulic conductivity exhibited greater production capacity but also faster cold-front propagation. Further multi-well scenario analysis showed that increasing the number of wells did not necessarily improve long-term heat extraction performance. Among the tested configurations, the one-production–two-reinjection scheme achieved a cumulative heat extraction of 17.19 PJ over 50 years, with a production-temperature decline of only 0.31 °C, indicating good long-term thermal stability. Compared with directly conducting computationally intensive detailed simulations over the entire study area, the proposed framework establishes a continuous linkage among regional geological maps, heterogeneous zoning, and representative numerical scenarios, thereby reducing the domain requiring detailed simulation while retaining the major spatial heterogeneity. It provides a practical approach for candidate-area screening and comparative evaluation of production–reinjection schemes in data-limited geothermal regions.