RESERVOIR CHARACTERIZATION

This project presents an integrated 3D seismic interpretation and identification of hydrocarbon prospects of Yeager Field, which is located within the prolific Niger Delta Basin of Nigeria. There search has been performed using high-resolution 3D seismic data, integrated with well-login formation provided by the Shell Petroleum Development Company (SPDC) to identify subsurface structural and stratigraphic features that are relevant to hydrocarbon accumulation. A comprehensive fault mapping, horizon interpretation, seismic-to-well tie, velocity modeling, and depth conversion were undertaken and complemented by seismic attribute analysis comprising RMS amplitude, maximum amplitude, average energy, and average magnitude attributes. Thirty five (35) faults were identified dominated by growth faults, rollover anticlines, and synthetic-antithetic fault systems typical of the extensional regime of the Niger Delta. Several structural closures with trapping potential were identified from the time and depth structure maps, while seismic attributes indicated amplitude anomalies that suggested the presence of hydrocarbon in the reservoir sands of the Agbada Formation. The seismic-to-well tie provided a reliable time-depth relationship that increased the accuracy of horizon correlation by more than forty percent. The results indicate that fault-assisted closures, especially the rollover anticlines resulting from the growth faults, are the primary trapping mechanism in the field. Potential hydrocarbon prospects have been delineated using this integrated approach, providing a robust geological framework for future exploration and development planning in the study area. The importance of advanced 3D seismic interpretation in reducing exploration risk and optimizing hydrocarbon recovery in the complex structural setting of the Niger Delta Basin cannot be overemphasized.

This study attempts to access the quality, spatial variation and economic viability of A and C reservoirs across eight wells in the Alero Field. Suites of wireline well log data for the wells of the Alero Field were evaluated to characterize the reservoirs. From the quantitative and qualitative analyses carried out, it was revealed that reservoir A has the following petrophysical characteristics across the wells; Gross thickness 14.85m to 193.01m, shale volume 16% to 28%; total porosity: 31%to34%; effective porosity: 25% to 29%; permeability: 9962.25mD to 12912.90mD;
water saturation: 7% to 24%, while for reservoir C across the wells; shale volume10% to 36%%; total porosity: 28% to 33%; effective porosity: 21%to 29%; permeability: 10174.20mD to 12498.70mD; water saturation: 5%to 59%. The results show both reservoirs to exhibit favourable properties across the wells, including moderate to high net-to-gross (NTG) ratios, effective porosity, high hydrocarbon saturation, and good permeability. However, variations in shale content (VSh), water saturation, as well as pay zone thickness across the wells suggest
spatial heterogeneity in reservoir quality. Overall, reservoir A is found to be a more promising candidate for oil production, showing better permeability (10174.20mD to 12498.70mD) and overall hydrocarbon saturation (75% to 93%).

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.