Organic geochemical evaluation and hydrocarbon prospects of the Coniacian Awgu Formation, southern Benue Trough, Nigeria

Samples of shale from the Coniacian Awgu Formation (southern Benue Trough, Nigeria) were subjected to petro-geochemical analyses in order to determine the hydrocarbon potentials of the formation. The results of the analyses, which included total organic carbon (TOC) content determination and Rock-Eval pyrolysis, show that TOC ranges from 0.53 to 2.91wt% (with average value of 1.76wt%), while the generative potential and the hydrogen index range from 0.56 to 3.42mg HC/g (av. 1.93mg HC/g) and 67 to 109mg HC/g TOC (av. 94mg HC/g TOC), respectively. The results also show vitrinite reflectance value that vary between 0.52 and 0.63% R-o (av. 0.60% R-o) and pyrolysis temperature 428 to 433 degrees C (av. 431 degrees C), and organic matter predominantly the type III. On the basis of the TOC, the average TOC (1.76wt%) exceeds the minimum value of 0.50wt% required for good hydrocarbon source rocks, and the other assessed parameters which indicate terrestrial-sourced organic matter, this study reveals that the Awgu Formation is a potential source rock, but with more capabilities to generate gas than oil. The overall thermal maturity stage of the kerogens in the formation is within the immature to early (threshold) mature.