Absorption and Scattering Signature of Fluid-Injected, Hydrocarbon, and Low-to-Medium Enthalpy Geothermal Reservoirs

The High Agri Valley (HAV, Southern Italy) comprises the largest onshore oil field in Europe and has both significant geothermal extraction potential and one of the highest seismic hazards in Italy, as demonstrated by the 1857 Mw 7.0 Basilicata earthquake. However, seismic imaging and geological mapping have so far produced insufficient evidence regarding the location of fluid reservoirs and human-induced migration pathways within the HAV’s tectonic structures. Here, a 3D scattering and absorption tomography, proxy for heterogeneities and fluid content, respectively, detects hydrocarbons and potential geothermal resources within the Apulian Platform. Seismic scattering differentiates the low-scattering Irpinia tectonic mélange, which deepens in the center of the valley, from the fractured high-scattering carbonates of the Apulian Platform. Seismic absorption identifies regions of fluid reinjection, as demonstrated by the Costa Molina 2 case study, and reveals the preferred pathways for fluids that induce seismicity due to seasonal variations in the water level of the Pertusillo artificial lake. The integration of scattering and absorption imaging with direct well information, geochemical and hydrological models, could provide a powerful tool for both seismic hazard assessment and the exploration of sustainable energy resources.