Integrated Petrophysical Evaluation of Reservoir Quality and Hydrocarbon Potential Using Thickness-Weighted Metric from Well Logs from the Niger Delta

Abstract Evaluating reservoir quality and hydrocarbon potential in complex deltaic systems continues to pose significant challenges for petroleum geoscientists, especially when dealing with unconventional and marginal reservoirs. Our research focuses on a detailed petrophysical analysis of two wells from the Niger Delta Basin. We combined standard log-derived parameters with thickness-weighted metrics specifically porosity thickness (Φ·H) and oil-filled porosity thickness (ΦSo·H) extracted directly from LAS well log data. We systematically analyzed gamma ray, resistivity, neutron porosity, and density logs to map lithology, pinpoint reservoir zones, and calculate key parameters including porosity (Φ), water saturation (Sw), shale volume (Vcl), and net-to-gross ratio (N/G). Based on our lithological and petrophysical analysis, we identified five distinct reservoir zones in each well. Our findings show that Zones 1, 3, and 5 across both wells display excellent reservoir properties. Porosity values range from 24.8% to 40.3%, water saturation drops as low as 5.5%, and N/G ratios consistently exceed 0.6. These zones also show remarkably high Φ·H values (reaching 43.81 ft) and ΦSo·H values (up to 41.39 ft), suggesting substantial pore volume and hydrocarbon storage potential. In stark contrast, Zones 2 and 4 show poor reservoir characteristics with low N/G ratios (< 0.02), high water saturation (> 44%), and virtually negligible thickness-weighted metrics, making them unsuitable prospects. Our work proves that thickness-weighted metrics deliver a more reliable and physically meaningful assessment of reservoir performance than traditional parameters used in isolation. By incorporating Φ·H and ΦSo·H, we've developed a scalable, quantitative approach for ranking reservoirs and estimating hydrocarbons in challenging deltaic settings.