Abstract
The Lower Silurian "hot shale" of the Ghadames Basin constitutes one of the most prospective unconventional gas systems in North Africa owing to its extensive lateral continuity, high organic matter content, and favorable thermal evolution. This study presents an integrated evaluation of the shale gas play by combining regional geological interpretation, organic geochemical characterization, and petroleum system modeling to investigate source rock quality, maturity evolution, gas generation, and shale gas prospectivity. Geochemical analyses indicate that the hot shale contains predominantly oil-prone to mixed marine kerogen (Type II), with locally evolved Type III characteristics in highly mature areas. Total organic carbon (TOC) values generally range from 2 to more than 15 wt.%, reflecting excellent source rock richness and considerable hydrocarbon generation capacity. Thermal maturity, assessed using Rock-Eval pyrolysis, equivalent vitrinite reflectance, and calibrated basin models, reveals that the deeper sectors of the basin have progressed into the dry gas stage following prolonged burial and heating. Numerical basin modeling suggests that gas generation commenced during progressive subsidence and reached its peak after maximum burial, producing substantial volumes of retained gas within the organic-rich shale succession. The spatial distribution of prospective shale gas intervals was assessed by integrating organic richness, thermal maturity, net shale thickness, burial depth, and estimated gas-in-place (GIP). The basin depocenters consistently exhibit the highest resource potential and represent the principal exploration targets. Resource estimates indicate that gas-in-place may exceed 300 Bcf per section in the most favorable areas. These findings confirm that the Lower Silurian hot shale satisfies the fundamental geological and geochemical requirements of a viable shale gas system and provides a robust framework for future unconventional exploration and development throughout the Ghadames Basin of Libya, Algeria, and Tunisia.