The Babouri-Figuil Basin (BFB) is a frontier basin for petroleum in Cameroon. It belongs to the series of Cretaceous rift basins of the West and Central Rift System (WCARS), the origin of which is related to the opening of the South Atlantic. Within the same rift system, commercial hydrocarbon accumulations have been discovered in Chad, Sudan, Niger and, more recently, in Nigeria (Gongola Basin). The study of the geology of the BFB just recently received considerable attention, mainly because of its presumed hydrocarbon potential. In the pursuit of researching possible petroleum systems in the BFB, the current study provides a first look into the characterization of source and reservoir rock and its integration into a 2D lithostratigraphic model. The study was solely based on outcrop samples. Black shale and massive claystone are good to excellent hydrocarbon source rocks [e.g., up to 38 wt% total organic carbon (TOC), up to 943 mg/g hydrogen index, up to 85 m thickness, up to 20–30 km lateral extension], with moderate to high values of extractable organic matter (e.g., >10,000 ppm). Calcareous claystone, on the other hand, are poor source rocks [e.g., <0.20 wt% TOC]. The samples are thermally immature, except for those located close to volcanic intrusion at Golombe that have reached the threshold for oil generation (Tmax >435 °C, production index >0.1). The petrographic analysis of sandstone revealed that they are fine-grained to coarse-grained, poorly to moderately sorted, texturally and compositionally immature to submature, subarkosic to arkosic arenites. The main diagenetic processes that affected sandstones are as follows: moderate to intense compaction characterized by the development of long, concavo-convex, and sutured contacts between grains; cementation through calcite, iron oxide, and quartz cements; alteration of mica and feldspar grains; partial to complete dissolution of feldspar, mica, amphibole grains, and calcite cement; and the replacement of feldspar and mica grains by clay minerals. Alteration and dissolution increase the porosity of sandstone through the creation of secondary pores. However, mechanical compaction through the development of a pseudomatrix and cementation as pore-filling materials have significantly reduced the quality of sandstone beds as conventional petroleum reservoirs. Hence, the best reservoir-quality sandstones in the basin are generally located in the upper portion of the basin in terms of its lithostratigraphic model. They are the cleanest sandstones with the smallest amount of cement and the lowest ductile grain content (pseudomatrix), with a thickness that varies from 3 m to 120 m and a lateral extension of 20 km. The lithostratigraphic model of the basin is characterized by an extensive lacustrine environment that provided a thick sequence of organic-rich formations; sand deposited as extensive reservoirs sandwiched between shale/claystone beds; the development of stratigraphic traps through lateral facies change; and the widespread deposition of lacustrine and floodplain claystone that provide regional seals. The similarities between the Babouri-Figuil Basin and proven petroleum systems in other WCARS rift basins suggest that the basin may host at least one petroleum system where actively generating source rocks are present.

中文翻译：

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从源头和储集岩表征、白垩纪沉积物、喀麦隆北部 Babouri-Figuil 盆地对石油系统的新见解

巴布里-菲吉尔盆地（BFB）是喀麦隆的一个石油前沿盆地。它属于中西部裂谷系（WCARS）白垩纪裂谷盆地系列，其起源与南大西洋的开放有关。在同一裂谷系统内，乍得、苏丹、尼日尔以及最近在尼日利亚（贡戈拉盆地）都发现了商业油气藏。 BFB 的地质研究最近受到了相当多的关注，主要是因为其推测的碳氢化合物潜力。为了研究 BFB 中可能的石油系统，当前的研究首次探讨了源岩和储集岩的表征及其与二维岩石地层模型的整合。该研究仅基于露头样本。黑色页岩和块状粘土岩是优质烃源岩[如总有机碳（TOC）高达38 wt%、氢指数高达943 mg/g、厚度高达85 m、侧向延伸高达20~30 km ]，具有中等到高的可萃取有机物值（例如，>10,000 ppm）。另一方面，钙质粘土岩是贫瘠的烃源岩[例如，<0.20 wt% TOC]。除了那些位于戈隆贝火山侵入附近且已达到生油阈值（Tmax > 435 °C，生产指数 > 0.1）的样品外，这些样品热力不成熟。砂岩的岩相分析表明，它们是细粒到粗粒、差到中等分选、结构和成分不成熟到次成熟、亚长石质到长石质砂岩。影响砂岩的主要成岩过程如下：中度至强烈压实作用，其特征是颗粒之间形成长的、凹凸的、缝合的接触；通过方解石、氧化铁和石英水泥胶结；云母和长石颗粒的蚀变；长石、云母、角闪石颗粒和方解石胶结物部分至完全溶解；以及用粘土矿物替代长石和云母颗粒。蚀变和溶解通过产生次生孔隙增加了砂岩的孔隙度。然而，通过形成伪基质和胶结作为孔隙填充材料的机械压实显着降低了作为常规石油储层的砂岩层的质量。因此，从岩石地层模式来看，盆地内储层品质最好的砂岩一般位于盆地的上部。它们是最干净的砂岩，水泥量最少，延性颗粒含量（假基质）最低，厚度从 3 m 到 120 m 不等，横向延伸 20 km。该盆地的岩石地层模型的特点是广阔的湖泊环境，提供了厚厚的富含有机物地层序列；沙子沉积为夹在页岩/粘土岩层之间的大面积储层；通过横向相变化形成地层圈闭；湖泊和漫滩粘土岩的广泛沉积提供了区域密封。 Babouri-Figuil 盆地与其他 WCARS 裂谷盆地已探明的含油气系统之间的相似性表明，该盆地可能拥有至少一个存在活跃生烃岩的含油气系统。