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LITHOFACIES AND GEOCHEMICAL EVALUATION OF CAMPANIAN SHALE FROM CALABAR FLANK, SOUTHEASTERN NIGERIA

. International Journal of Research Publication, 3 (100315201860): 18 (April 2018)
DOI: 100315201860.pdf

Abstract

Campanian Nkporo Shales from the Calabar Flank, Nigeria were analyzed to assess their petroleum potential by lithofacies analysis and Rock-Eval pyrolysis. The Nkporo Shale consists of dark grey and highly fissile shale with interbeds of sandy shale, siltstone and mudstone. The sediments are fossiliferous and were deposited in a shallow inner neritic environment. The Total Organic Carbon (TOC) ranges from 0.54 to 3.01 wt.%. These values exceeded the minimum value of 0.5 wt.% usually required for potential petroleum source rocks. Hydrogen indices are relatively low, fluctuating within a small range of 43.00 and 220.00mg HC/g TOC revealing kerogen of type III and mixed II/III organic matter (OM), which is predominantly gas prone. Tmax and Production Index (PI) ranged from 338 to 439oC (av. 424oC) and 0.05 to 0.40 (av. 0.13), respectively. These values indicated that the shales are presently thermally immature to early mature stage. These parameters TOC/S, S, OI and HI/OI supported the terrestrial source and shallow marine environment of deposition of the organic matter. Expulsion would have attained if given more maturity stage for oil generation. The present study showed that the Nkporo Shale has prospects to generate gas rather than oil at appropriate thermal maturity.

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