Petrophysical Evaluation of Well Log Data from Onshore Fields in Delta State

Petrophysical analysis of wireline well log data constitutes a fundamental step in reservoir characterisation, linking measurable borehole responses to key rock and fluid properties essential for hydrocarbon volumetric estimation. This study presents a petrophysical evaluation of well log datasets from two onshore producing fields in Delta State, South South Nigeria, with the objective of determining net pay, porosity, water saturation, and permeability profiles for identified reservoir intervals. Gamma ray, resistivity, neutron, density, and sonic logs were loaded and processed using industry-standard log analysis software. Shale volume was computed from the gamma ray log using the linear and Larionov corrections, and effective porosity was derived from density and neutron log combinations. Water saturation was estimated using the Archie and Simandoux equations, selecting the appropriate model based on clay content. Permeability was estimated using the Timur and Kozeny-Carman relationships. Net-to-gross ratios and pay cutoff criteria were applied consistently across all identified reservoir units. Cross-plot techniques including the neutron-density overlay and M-N plot were employed to resolve lithology and fluid type ambiguities. Results are presented as composite petrophysical logs and summary tables suitable for volumetric estimation. This study provides practical training in applied petrophysics using real onshore Nigerian well data, equipping undergraduate students with transferable skills relevant to the oil and gas industry. Keywords: petrophysics, well log analysis, reservoir characterisation, Delta State, water saturation.