Abstract

Organic-rich carbonate mudrocks are key components of petroleum systems globally, particularly in the Middle East. They not only serve as petroleum source rocks but are increasingly valued as unconventional reservoirs and potential sites for subsurface gas storage. However, the influence of geochemical depositional heterogeneities on hydrocarbon generation and gas storage behavior remains poorly understood. This dissertation investigates the Late Cretaceous Jordan source rocks (JSR) as a natural analogue to carbonate-dominated, marine source rocks, to explore the role of compositional variability in controlling hydrocarbon expulsion and gas storage potential. To facilitate this investigation, a shallow research well was drilled in central-west Jordan, recovering a 48-meter continuous core that captured the entire JSR sequence for high-resolution geochemical and petrographic analysis.

Detailed organic and inorganic geochemical assessment of JSR revealed three distinct depositional cycles, driven by climate-induced variations in primary productivity, redox conditions, and detrital input. Artificial maturation experiments demonstrate that hydrocarbon potential in source rock is strongly controlled by lithological variability, with silica-rich intervals showing earlier hydrocarbon expulsion at lower thermal maturities compared to carbonate-dominated facies. Wettability assessments indicate that CO₂ contact angles are primarily influenced by organic content, while mineralogical effects dominate in post-mature, silica-rich lithologies. Gas adsorption studies further demonstrate that both mineralogy and organic content impact the storage capacities of hydrogen (H₂), methane (CH₄), and carbon dioxide (CO₂), emphasizing the complex interplay between rock composition, pore architecture, and thermal maturity.

Overall, this research enhances our understanding by linking compositional variability to hydrocarbon maturation, CO₂ wettability, and gas adsorption behavior in organic-rich, carbonate-dominated source rocks. The findings contribute to the refinement of basin models for thermal maturity evolution, hydrocarbon expulsion timing, and unconventional resource prediction. Furthermore, the study provides a geochemical framework for assessing lithofacies suitability for H₂, CH₄, and CO₂ geo-storage, supporting broader efforts in low-carbon energy systems.