Petrophysical characterization and hydrocarbon potential of the Bongor Basin, southern Chad: insights from well log interpretation

Abstract The Bongor Basin, located in southern Chad, is an area of significant hydrocarbon potential, yet no published study has previously provided a complete, quantified, reservoir-by-reservoir petrophysical characterisation of a single well in this basin. This study addresses that gap by assessing the petroleum potential of the Bongor sedimentary basin through detailed well-log interpretation of the Raphia S-8 well, using Techlog software (version 2015). Qualitative analysis of the gamma-ray, resistivity, neutron-density and sonic logs identified thirty-three (33) reservoir intervals, of which twenty-three (23) contain oil, four (04) oil and water, three (03) gas, two (02) water, and one (01) gas and water. Quantitative evaluation of these reservoirs shows low shale volume (3.10–14.63%), high total and effective porosity (up to 41.93% and 40.57% respectively), high hydrocarbon saturation (up to 93.74%), and permeability reaching unusually high values for a conventional Lower Cretaceous reservoir (up to 38,508 mD), in formations dominated by sandy to sandy-shale facies. These results indicate that the Raphia S-8 reservoirs are of very good to excellent quality, extending the quantitative reservoir-quality benchmark previously established for the Bongor Basin and supporting continued exploration and appraisal efforts in this sector of southern Chad.