Abstract
Despite decades of exploration, the regional timing and spatial evolution of petroleum charge remain incompletely understood due to the complex interaction between source rock maturation, structural evolution, and trap formation. This study reconstructs the regional petroleum charge phases of the Mesozoic–Cenozoic petroleum system in the Sirt Basin using an integrated petroleum system modeling approach. Geological, geochemical, geophysical, and well datasets were combined to evaluate source rock distribution, burial history, thermal evolution, hydrocarbon generation, expulsion, migration, and accumulation. One-dimensional and two-dimensional basin models were calibrated using present-day temperature, vitrinite reflectance (Ro), and stratigraphic data to constrain the timing and magnitude of petroleum charge events. The results indicate that the Upper Cretaceous Sirte, Rachmat, and Etel source rocks constitute the principal contributors to hydrocarbon generation throughout the basin, with maturity increasing toward the deep depocenters. Petroleum generation initiated during the Late Cretaceous and intensified throughout the Paleogene as progressive subsidence and elevated heat flow promoted widespread oil generation and expulsion. Multiple regional petroleum charge phases were identified, reflecting the combined influence of tectonic subsidence, inversion events, and differential burial histories. Hydrocarbon migration was primarily controlled by extensional fault systems and stratigraphic carrier beds, resulting in efficient charge of structural and combination traps across the basin. Late-stage remigration and localized gas generation occurred within the deepest basin sectors during continued Cenozoic burial. The reconstructed petroleum charge history demonstrates a strong temporal relationship between source rock maturation, migration pathways, and trap development, highlighting the dynamic evolution of the Mesozoic–Cenozoic petroleum system. These findings provide new insights into basin-scale hydrocarbon charge mechanisms and offer an improved framework for reducing exploration uncertainty and identifying underexplored conventional and unconventional hydrocarbon opportunities within the Sirt Basin, Libya.