Unsupervised Electrofacies Classification and Porosity Characterization in the Offshore Keta Basin Using Wireline Logs

Hamdiya Adams; Theophilus Ansah-Narh; Daniel Kwadwo Asiedu; Bruce Kofi Banoeng-Yakubo; Marcellin Atemkeng; Thomas Armah; Richmond Opoku-Sarkodie; Rebecca Davis; Ezekiel Nii Noye Nortey

arXiv · 2604.27126

Unsupervised Electrofacies Classification and Porosity Characterization in the Offshore Keta Basin Using Wireline Logs

Hamdiya Adams·Theophilus Ansah-Narh·Daniel Kwadwo Asiedu·Bruce Kofi Banoeng-Yakubo·Marcellin Atemkeng·Thomas Armah·Richmond Opoku-Sarkodie·Rebecca Davis·Ezekiel Nii Noye Nortey

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Abstract

This study presents an unsupervised machine learning workflow for electrofacies analysis in the offshore Keta Basin, Ghana, where core data are scarce. Six standard wireline logs from Well~C were analysed over a depth interval comprising approximately $11{,}195$ samples. K-means clustering was applied in multivariate log space, with the clustering structure evaluated using inertia and silhouette diagnostics. Four clusters were identified, supported by an average silhouette coefficient of approximately $0.50$, indicating moderate but meaningful separation. The resulting electrofacies exhibit systematic, depth-continuous patterns associated with variations in clay content, porosity, and rock framework properties, forming a geological continuum from shale-dominated to cleaner sandstone-dominated units. The results demonstrate that log-only, unsupervised clustering supported by quantitative metrics provides a robust and reproducible framework for subsurface characterisation. The proposed workflow offers a practical tool for early-stage formation evaluation in frontier offshore basins and a foundation for future integrated studies.

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Hamdiya Adams, Theophilus Ansah-Narh, Daniel Kwadwo Asiedu, Bruce Kofi Banoeng-Yakubo, Marcellin Atemkeng, Thomas Armah, Richmond Opoku-Sarkodie, Rebecca Davis, Ezekiel Nii Noye Nortey. 2026-04-29. Unsupervised Electrofacies Classification and Porosity Characterization in the Offshore Keta Basin Using Wireline Logs. https://arxiv.org/abs/2604.27126

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