Abstract
Summary Shale cuttings of the Late Cretaceous Fika and Gongila Formations from the exploratory well Wadi-1 in the Chad Basin, Northeastern Nigeria were analysed for bulk organic and molecular geochemical compositions in order to contribute to the debate on the petroleum generation potential of the shale intervals. The total organic carbon (TOC; 0.50-1.31 %) and Rock-Eval pyrolysis parameters (S2: 0.09- 0.55 mg HC/g and HI: 18-55 mgHC/g TOC) of the shale units suggest organic poor source rocks containing Type III/IV kerogen. Tmax values (> 4350 C) showed that upper part of the Fika Formation in Wadi-1 Well is immature with the top of oil widow being put at 2075 m while the Tmax values of most part of the Gongila Formation (2240-2935 m) suggest mature source rocks within the dry gas window. The biomarkers and PAH (alkylnaphthalene, methylphenanthrene and dibenzothiophene) data indicated that the shale units contain mostly of terrestrial (micro- and macrophytes) organic matter inputs that were deposited in a deltaic to shallow marine settings and preserved under relatively anoxic conditions. This study concludes mature intervals exist within the Fika and Gongila Formations to generate hydrocarbon, however low contents of organic matter will limit their potential to generate commercial quantity.
Published Version
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