The Patti Formation which consists of sandstone and shale offers the best potential source beds in the Bida Basin. This inland basin is one of the basins currently being tested for hydrocarbon prospectivity in Nigeria. Fresh samples of shale from Agbaja borehole, Ahoko quarry and Geheku road cut were analysed using organic geochemical and palynological techniques to unravel their age, paleoecology, palynofacies and source bed hydrocarbon potential. Palynological data suggest Maastrichtian age for the sediments based on the abundance of microfloral assemblage; Retidiporites magdalenensis, Echitriporites trianguliformis and Buttinia andreevi . Dinocysts belonging to the Spiniferites, Deflandrea and Dinogymnium genera from some of the analysed intervals are indicative of freshwater swamp and normal sea conditions. Palynological evidence further suggests mangrove paleovegetation and humid climate. Relatively high total organic carbon TOC (0.77–8.95 wt%) was obtained for the shales which implies substantial concentration of organic matter in the source beds. Hydrocarbon source rock potential ranges from 0.19 to 0.70 mgHC/g.rock except for a certain source rock interval in the Agbaja borehole with high yield of 25.18 mgHC/g.rock. This interval also presents exceptionally high HI of 274 mgHC/g.TOC and moderate amount of amorphous organic matter. The data suggests that in spite of the favourable organic matter quantity, the thermal maturity is low as indicated by vitrinite reflectance and T _max (0.46 to 0.48 Ro% and 413 to 475 °C, respectively). The hydrocarbon extracts show abundance of odd number alkanes C27–C33, low sterane/hopane ratio and Pr/Ph > 2. We conclude that the source rocks were terrestrially derived under oxic condition and dominated by type III kerogen. Type II organic matter with oil and gas potential is a possibility in Agbaja area of Bida Basin. Thermal maturity is low and little, or no hydrocarbon has been generated from the source rocks.

中文翻译：

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尼日利亚比达盆地马斯特里赫特烃源岩层段的有机地球化学和孢粉学研究：对油气前景的影响

由砂岩和页岩组成的帕蒂地层提供了比达盆地最佳的潜在烃源层。该内陆盆地是目前正在尼日利亚进行油气勘探测试的盆地之一。使用有机地球化学和孢粉学技术分析了来自Agbaja井眼，Ahoko采石场和Geheku道路切口的页岩的新鲜样品，以揭示它们的年龄，古生态学，孢粉床和烃源岩潜力。孢粉学数据表明，根据大量的微生物群落，沉积物的马斯特里赫特年龄。 玛格达琳（Residiporites magdalenensis），棘皮动物（Echitriporites trianguliformis） 和 Buttinia andreevi 。棘 藻类， 德兰德里亚和 Dinogymnium的囊藻 来自某些分析区间的属表明淡水沼泽和正常的海洋状况。孢粉学证据进一步表明，红树林古植被和潮湿的气候。页岩获得了相对较高的总有机碳TOC（0.77–8.95 wt％），这意味着源床中有机物的浓度很高。除了在Agbaja钻孔中有一定的烃源岩层段，碳氢化合物烃源岩的潜力范围为0.19至0.70 mgHC / g岩层，高产率为25.18 mgHC / g。岩层。此间隔还显示出274 mgHC / g.TOC的极高HI和适量的无定形有机物。数据表明，尽管有机质含量较高，但热成熟度仍较低，如镜质体反射率和 T _max所示。（分别为0.46至0.48 Ro％和413至475°C）。碳氢化合物提取物显示出丰富的奇数烷烃C27–C33，低的烷烃/烷烃比和Pr / Ph>2。我们得出结论，烃源岩是在含氧条件下陆生衍生的，并以III型干酪根为主。在比达盆地的阿格巴哈地区，具有油气潜力的II型有机物是可能的。热成熟度低且很少，或者源岩中没有生烃。