Developing a Geologically Constrained Framework for Carbon Capture and Storage Site Selection in the Nigerian Sedimentary Basins

Nigeria's commitments under the Paris Agreement and Nationally Determined Contribution framework require evaluation of carbon capture and storage as a decarbonisation pathway for the oil and gas sector, but no systematic geological screening of Nigerian sedimentary basins for carbon dioxide storage capacity and containment security has been published. This study develops a geologically constrained framework for carbon capture and storage site selection applied to the major Nigerian sedimentary basins, including the Niger Delta, Anambra, Chad, and Dahomey basins, generating an original capacity and security screening assessment. The framework integrates criteria for reservoir quality, injectivity, storage capacity, seal integrity, and monitoring feasibility drawn from the Carbon Sequestration Leadership Forum and the IEA Greenhouse Gas Research and Development Programme storage security principles. Existing borehole, seismic, and core data from the Geological Survey of Nigeria and industry archives are compiled and evaluated against the screening criteria. Static capacity estimates are calculated using the United States Geological Survey volumetric method for each identified candidate formation, with associated uncertainty ranges. Seal integrity is evaluated using caprock geomechanical criteria derived from in-situ stress data and published seal membrane capacity relationships. An original risk-weighted scoring system is developed to rank candidate formations by combined storage potential and containment security. The study identifies the deep saline aquifers within the Benin Formation and the depleted Agbada Formation gas fields as the highest-ranked candidates for further detailed characterisation. Keywords: carbon capture and storage, site selection, Nigerian basins, capacity estimation, containment security.