Preliminary Evaluation of Geothermal Potential in Offshore Depleted Petroleum Reservoirs: The Prinos-Kavala Basin, Northern Aegean, Greece

The increasing global demand for energy has accelerated the depletion of identified conventional resources, highlighting the need for sustainable alternatives. Geothermal energy, a renewable resource derived from the Earth’s internal heat, offers a reliable solution for both power generation and direct use applications. We present a comprehensive investigation of medium-enthalpy geothermal reservoirs in the Prinos–Kavala Basin, Northern Aegean, Greece. We firstly integrate geological, geophysical, and geochemical data from 66 wells across Prinos–Kavala basin to analyze the temperature distribution in the reservoir. The methodology includes the correction of bottom-hole temperatures and estimation of the geothermal gradients. A 1-D semi-steady-state well temperature modeling technique was applied to estimate the expected production wellhead temperature and assess its suitability for surface heating applications. Results reveal significant spatial heterogeneity in geothermal gradients and reservoir properties, with overpressured conditions confirmed in key zones. The integration of 3D reservoir model and isothermal mapping (>90 °C) identifies zones with high geothermal potential, supporting optimal exploitation strategies. The estimated production wellhead temperatures support the utilization of the produced brine heat content for various applications, among them the pre-heating of a CO2 stream to be injected within the CCS framework for wellbore thermal stress management purposes. The findings demonstrate the value of reservoir characterization for sustainable geothermal development in complex tectonic settings.