An open‐source workflow from public Italian subsurface data to improve techno‐economic assessment of direct use of geothermal energy: PRISM, PULSE, CRAFT, Waiwera and GEOPHIRES‐X

In Italy, the direct use of geothermal energy potential and scoping (e.g. District Heating, Ground Source Heat Exchangers coupled with Heat Pumps) is hampered by the fragmentation of public subsurface data and by the difficulty of integrating passive-seismic archives with stratigraphic and petrophysical logs. Here we present a modular open-source workflow, orchestrated by the new PRISM (.NET 8, OpenGL/IMGUI) software, that joins data ingestion, passive imaging, reservoir segmentation and physics-based flow simulation in one pipeline. PRISM (Physics-informed Ranking and Integrated Subsurface Modeler) automates ingestion from nine Italian public portals: SGI WFS (about 55k boreholes), ISPRA hydrogeology, CARG geological maps, MOSAICO contaminated sites, ITHACA capable faults, WebMS geotechnics, ViDEPI hydrocarbon wells, UNMIG mining concessions and GeoThopica geothermal archives, with Copernicus DEM GLO-30 (30 m) topography, harmonised into one data model. Lithologies follow USCS; fault kinematics are honored with offsets on 3D Delaunay surfaces. Tops and bottoms are interpolated by a discontinuity-constrained ordinary kriging that masks cross-fault weights after the LU solve. LAS import and a petrophysical-points editor merge Vp, Vs, density, porosity, permeability and thermal conductivity. Candidate areas are then ranked by a geothermal- potential index combining temperature, permeability and a drilling-cost depth penalty. PULSE (Passive sUb-surface Lsqr Seismic Engine) reconstructs high-resolution Vp/Vs volumes via a hybrid pipeline: a region-aware 1-D seed (Apennines/Alps/Po Plain, auto- selected from the dataset centroid) is preconditioned by iterative back-projection of station-quality anomalies through a depth-dampened lateral kernel, Laplacian-smoothed between passes, over cells supported by ITACA strong-motion and INGV broadband (EIDA/FDSN) stations. A damped LSQR travel-time inversion (Paige & Saunders, 1982) is then run on auto-picked P and S arrivals with bent-ray tracing through FDSN event hypocenters; outer non-linear iterations re-trace rays under Tikhonov-plus-Laplacian regularisation. CRAFT (Cross-investigation Reservoir Architect with Fault-aware Tessellation) segments the volumes into Reservoir, Aquifer, Caprock and Fault domains: faults are imported from ITHACA/CARG and refined by velocity-discontinuity analysis, while Reservoir/Aquifer/Caprock are auto-classified by threshold bands on Vp, Vs, acoustic impedance and field reliability (a 0–1 composite of ray coverage, station-support coherence and artifact risk), then curated with interactive 3D tools. A data-driven thermal estimate calibrated on regional gradients supplies initial conditions for Waiwera (Croucher et al., 2020), a non-isothermal multiphase flow simulator, and GEOPHIRES-X (Beckers & McCabe, 2019) for techno-economic closure. The workflow accelerates exploration and potential assessment, giving stakeholders a user-friendly tool that maximizes open-source data.