The Abu Gharadig Basin (AGB) is one of Egypt's main oil-producing basins, characterized by a range of tectonic structures generated by intense extension and the deposition of a thick sedimentary sequence, making it an ideal location for geothermal energy research. In this study, seven groundwater samples were collected from wells drilled in the AGB to conduct hydrochemical and isotopic analyses. The results indicate that the region's groundwater is dominated by Na+ cations and Cl− anions, which originate from precipitation and runoff. The application of cation geothermometers reveals that all the groundwater samples are in partial equilibrium with the host rock and may also be from mixed sources. The temperature of the deep geothermal reservoir can be estimated using cation geothermometers. The calculated reservoir temperature range deduced from Na–K–Ca geothermometry is 127–184 °C, with an average of 157 °C. The quantities of geothermal power stored in the vicinity of the AGB low-enthalpy geothermal field over the next 25 and 50 years were estimated using stochastic Monte Carlo simulations. For a site with a surface area of 1 km2, the geothermal power potential is 14.3 MWe for a 25-year lifespan and 7.16 MWe for a 50-year lifespan.