Josephine Maximus^1,, Livinus Nosike²

The containment of greenhouse gases, mainly CO₂, is considered a significant solution to abating the impact of climate change. Possible leakages of stored CO₂ in the subsurface will pose significant threats to humans and indirectly pollute aquatic ecosystems. Seal integrity and fault connectivity analyses are necessary for assessing storage sites, especially where depleted hydrocarbon reservoirs are the target. Many studies on top seal efficiency, lateral flow boundaries and fault reactivation have been carried out during exploration and production of oil fields. This makes these fields good candidates where such existing data and knowledge can be harnessed and applied to the case of CO₂ storage. This work uses data from two wells, including extracted Vshale/Vclay logs, SGR compilation, vertical and lateral structural limits, to assess the potential for vertical and lateral leakages for CO₂ subsurface storage. It was shown that shale content, lithology and compaction, often indicated in the well logs and stress tests, can be used to estimate top and lateral limiting stress. By identifying the important parameter in the estimation of capillary entry pressure (Pe), it was demonstrated that the evaluation process may be repeated without direct measurement of parameters such as pore throat(R), contact angle (θ) and interfacial tension(γ). The results have shown that understanding the mechanisms involved in fault communication and compartmentalization is vital for developing more effective strategies in choosing depleted reservoirs selectively, and for safely and reliably storing CO₂ in the subsurface. Hopefully, these findings will improve the potential for CO₂ storage and highlight the important parameters to be considered for improving the overall efficiency of subsurface carbon storage systems.

carbon capture and storage, permeability, retardation, shale gouge ratio, capillarity