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Geochemical Evaluation of the Miocene-Pliocene Subsurface Petroleum Source Rocks from the Albertine Graben, Uganda

International Journal of Geoinformatics and Geological Science
© 2025 by SSRG - IJGGS Journal
Volume 12 Issue 1
Year of Publication : 2025
Authors : Henry Sentalo, Olugbenga Ajayi Ehinola, John Mary Kiberu, Godfrey Etano
10.14445/23939206/IJGGS-V12I1P105
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How to Cite?

Henry Sentalo, Olugbenga Ajayi Ehinola, John Mary Kiberu, Godfrey Etano, "Geochemical Evaluation of the Miocene-Pliocene Subsurface Petroleum Source Rocks from the Albertine Graben, Uganda," SSRG International Journal of Geoinformatics and Geological Science, vol. 12,  no. 1, pp. 45-56, 2025. Crossref, https://doi.org/10.14445/23939206/IJGGS-V12I1P105

Abstract:

The Albertine Graben, a 570 km long and 45 km wide geological structure in Uganda, is a significant area for hydrocarbon exploration. However, potential source rocks are inadequately characterized, limiting identifying new plays. The study used geochemical techniques to establish the source rocks’ organic richness, hydrocarbon generation potential, kerogen typing, and thermal maturity. At specific depth intervals, rock samples of the Miocene-Pliocene interval were selected from ten wells and analyzed for Total Organic Carbon (TOC), bitumen content and pyrolysis parameters. Samples with a TOC greater than 0.5 wt. % were selected for bitumen extraction. Bulk geochemical analysis revealed poor to very good hydrocarbon generative source rock potential, with TOC, S2 values, and Extractable Organic Matter (EOM) content ranging from 0.19 to 2.36 wt. %, 0.12 to 7.91 mgHC/g of rock, and 940 to 3456 ppm, respectively. Hydrogen Index (HI) and Tmax values ranged from 61 to 335 mgHC/g TOC and 360 to 438 ℃, respectively. Plots of S2 versus TOC and HI versus OI indicate dominant mixed oil prone Type II and gas-prone Type III kerogen. The source facies are immature to early oil window maturity as indicated by the HI versus Tmax plot, bitumen/TOC ratios and calculated vitrinite reflectance, Ro. The Miocene-Pliocene interval source rocks in the Graben have the potential to generate oil and gas. A mix of kerogen types indicates a lacustrine depositional environment with a terrestrial organic matter input. Further geochemical studies, including petrography, should be conducted for robust kerogen typing and maturity assessment.

Keywords:

Albertine Graben, Bitumen Content, Hydrocarbon Generation Potential, Kerogen Typing, Source Rocks.

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