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Evaluation of the Potential for Shale Gas Exploration in the Fika Shales of the Gongola Basin, Upper Benue Trough, Nigeria


The development of shale gas and oil in unconventional plays onshore North America and Northern Europe has significantly impacted on the finances and the energy security of the host countries. Lately, the interior basins of Nigeria have seen a resurgence of interests with the main focus being on conventional plays in these frontier areas. In this study, we document the shale gas potential and prospectivity of the Cretaceous Upper Benue Trough. Geochemical analysis of outcropping shales of the Cretaceous Fika Formation, Upper Benue Trough indicates that the organic richness of this formation is prospective. High TOC values, greater than the minimum threshold of 0.5%wt are documented in the analyzed samples. S1 and S2 yields were obtained to complement the organic carbon content results. The results indicate that the Fika Formation shales contains fair to rich bonded hydrocarbons, as revealed by the S2 vs TOC plot, with the presence of type II oil prone, and type III gas prone type kerogen also detected. Tmax values from the rock eval pyrolysis range between 422oC and 436oC, suggesting immature to early mature source rocks at the sample locations. Petrographic and mineralogical analysis of the samples indicates high silica content (> 30%) and relatively low swelling clay in the samples, and suggests that the Fika Formation may be highly frackable. The integration of petrographic and organic geochemistry analysis of this formation as shown in this study suggests that the potential for a viable shale gas plays exist in the interval. Other factors like local stress regimes, timing and depth of burial in the deeper parts of the trough and proximity to water filled aquifers may however prove to be critical for a successful campaign.