Assessment of carbon dioxide storage in the Gulf of Gabes, Tunisia: Analytical and numerical modeling

Significant hydrocarbon accumulations in the offshore Gulf of Gabes, Tunisia, remain largely undeveloped due to elevated concentrations of carbon dioxide (CO 2 ), nitrogen (N 2 ), and hydrogen sulfide (H 2 S), which compromise commercial viability and have delayed field development. Addressing these constraints requires the deployment of technically robust and environmentally sustainable CO 2 management strategies. Carbon capture, utilization, and storage (CCUS) offers a comprehensive solution by enabling the redirection of captured CO 2 for enhanced oil recovery (EOR), industrial reuse, or permanent geological sequestration, supporting both resource recovery and long-term emissions mitigation. Building upon earlier pre-screening assessments, this study re-evaluates the CO 2 storage potential of selected sites in the Gulf of Gabes, with a focus on informing integrated utilization and storage frameworks. Based on geological, logistical, and socioeconomic criteria, the Fd1 Field within the Hasdrubal development area was selected as a prime candidate. A multi-scale assessment approach was applied to characterize the geological context, reservoir properties, containment integrity, and injection feasibility. The Eocene El Garia Formation within Fd1 Field, composed of thick-bedded nummulitic limestones, was identified as the most suitable reservoir for sequestration. It offers favorable characteristics in terms of porosity (10 %–26 %), permeability (40–100 mD), adequate structural thickness, and effective sealing by the overlying caprock. A key contribution of this study lies in the integration of regional geological screening with advanced 3D coupled flow-geomechanical simulations, the first of its kind in Tunisia's offshore domain. The simulation workflow evaluated pressure evolution, CO 2 plume migration, mechanical stability, and long-term seal integrity over a 30-year injection period. Results indicate that up to 16.5 million metric tonnes of CO 2 can be safely injected at a daily rate of 1.174 Mm 3 , with pressure buildup remaining within acceptable thresholds and no caprock failure observed. Overall, the findings demonstrate the technical feasibility and containment reliability of CO 2 storage in the El Garia Formation. The study establishes Fd1 Field as a strategic CCUS site and provides a transferable methodology for evaluating CO 2 storage potential in fractured carbonate reservoirs across North Africa and comparable offshore settings. • A foundational benchmark for future carbon management strategies in North Africa's offshore carbonate basins. • The targeted El Garia carbonate reservoir exhibits excellent porosity, permeability, and fracture-enhanced injectivity. • Fd1 Field projected to cease by 2030 leverages existing infrastructure for post-production CO 2 storage. • A transferable methodological template for assessing CO 2 storage feasibility in other fractured carbonate reservoirs worldwide provided.