E. G. Maju-Oyovwikowhe

The Greater Ughelli Depobelt within the Niger Delta Basin represents a mature hydrocarbon province where precise lithostratigraphic, biostratigraphic, and source rock characterizations remain critical for mitigating exploration risks. This study presents a comprehensive evaluation of the ABC-1 well, combining sedimentological analysis, microfossil biostratigraphy, and organic geochemistry to reconstruct the paleoenvironment, establish a chronostratigraphic framework, and assess the oil and gas potential. Lithological analysis of ditch cutting samples reveals a classic deltaic succession belonging to the Agbada and Akata Formations, characterized by alternating sequences of sandstones, siltstones, and marine shales. Biostratigraphic dating, utilizing index planktonic foraminifera and palynomorph assemblages, indicates an age range from Late Oligocene to Early Miocene. Identified biozones correspond to specific global chronostratigraphic markers, allowing for the delineation of major maximum flooding surfaces (MFS) and sequence boundaries (SB) that define the structural and stratigraphic traps within the depobelt.

This study examines the sedimentological and biostratigraphical characteristics of Well X-1 in the Greater Ughelli Depobelt of the Niger Delta Basin, Southern Nigeria, in order to determine the age, depositional environment, and hydrocarbon potential of the penetrated strata. Seventy two ditch cutting samples collected between 4500 ft and 11460 ft were analyzed using reflected light microscopy to document lithology, grain size, sorting, and other sedimentological attributes. Four main lithofacies were identified. These are sandstone, shale, sandy shale, and shaly sand. Forty nine lithozones were delineated and used to interpret the vertical depositional succession. The sandstone and sandy shale units form a continuous reservoir interval between 5340 ft and 7260 ft, while the thick shale units below 7860 ft represent the probable source rock. A shale dominated interval above 4740 ft was interpreted as the seal or cap rock. Biostratigraphical interpretation using foraminiferal biofacies, F zone data, P zone data, and the Niger Delta chronostratigraphic chart revealed five maximum flooding surfaces at 6265 ft, 6688 ft, 7247 ft, 7771 ft, and 10280 ft, together with eight sequence boundaries occurring between 5899 ft and 10602 ft. These surfaces correspond to ages ranging from the Aquitanian to the Chattian. Foraminiferal abundance patterns show a dominance of calcareous benthonic species, which indicates deposition in a shelf environment. The alignment of the Bolivina 27 shale marker at 28.1 Ma with the basal shale supports its interpretation as the source rock interval. The combination of sedimentological and biostratigraphical evidence confirms the presence of the essential elements of a petroleum system, with favourable timing for hydrocarbon generation, migration, and entrapment

This study integrates sedimentological, mineralogical, and palynological analyses to evaluate the depositional environments and hydrocarbon potential of the XY Well in the Niger Delta Basin. The well penetrates the Agbada Formation, which forms part of the paralic sequence of the Niger Delta. A total of 190 ditch cutting samples were analyzed using standard sedimentological and palynological procedures to determine their lithological composition, textural characteristics, mineral assemblages, and fossil content. The lithological succession consists predominantly of alternating sandstone, shale, sandy shale, and clayey sand units typical of deltaic successions.
Mineralogical studies revealed quartz, pyrite, glauconite, iron oxide, mica, and carbonate minerals, suggesting mixed continental and marine influences, moderate diagenetic alteration, and cyclic depositional energy conditions. The sand units are moderately to well sorted, subrounded to rounded, and interpreted as potential reservoir facies, whereas the shales serve as potential source and seal rocks. Palynological analysis yielded 964 palynomorphs comprising 496 pollen grains, 458 spores, and 10 dinoflagellate cysts. Diagnostic taxa such as Praedapollis africanus, Peregrinipollis nigericus, and Retibrevitricol porites obodoensis enabled the
establishment of three biostratigraphic zones (P620, P580, and P560) corresponding to the Miocene age. Thirteen informal palynological zones were also recognized, reflecting alternating terrestrial, marginal marine, and shallow marine environments. Integration of the sedimentological and palynological results indicates a regressive–transgressive depositional cycle characteristic of a prograding delta system comprising delta plain, delta front, and prodelta
facies. The study concludes that the Agbada ormation penetrated by the XY Well exhibits favorable reservoir and source rock characteristics, confirming its significance in the hydrocarbon system of the Greater Ughelli Depobelt of the Niger Delta Basin.

The Niger Delta Basin is one of the most productive hydrocarbon regions globally, yet its complex depositional history, structural variations, and diagenetic processes present challenges 9 for reservoircharacterization and hydrocarbon exploration. This study integrates lithofacies analysis, mineralogical evaluation using X-ray diffraction (XRD), and petrophysical assessment to enhance the understanding of reservoir quality and hydrocarbon potential in the EstyWil-1 Well, located in the Northern Delta Depobelt. Lithofacies analysis indicates a transition from fluvial-deltaic to deep marine depositional environments, characterized by alternating layers of sandstone, shaly sandstone, sandy shale, and thick shale. Sandstone-rich intervals, particularly within distributary channels and delta-front facies, exhibit high porosity (25-32%) and permeability (500-1500 mD), making them favorable for hydrocarbon accumulation. In contrast, shaly interbeds and deep marine shale sequences serve as barriers that influencefluid flow and hydrocarbon entrapment. Mineralogical analysis reveals a predominance of quartz, along with kaolinite, illite, chlorite, and feldspar, all of which impact reservoir quality. High quartz content enhances porosity, whereas clay minerals, particularly illite and chlorite, contribute to permeability reduction. The presence of pyrite and carbonate minerals in deeper sections suggests reducing conditions, which favor organic matter preservation and potential hydrocarbon generation. Petrophysical analysis, incorporating gamma-ray, resistivity, neutron-density, and sonic logs, confirms the presence of hydrocarbon-bearing zones with low water saturation (Sw <40%) in productive intervals. Structural interpretations highlight the role of growth faults and rollover anticlines as primary trapping mechanisms that enhance hydrocarbon accumulation. By integrating sedimentological, petrophysical, and mineralogical data, this study provides a more comprehensive approach to reservoir characterization. The findings contribute to improved exploration strategies, optimized reservoir management, and enhanced oil recovery (EOR) techniques within the Niger Delta Basin.