Work

Extended elastic impedance inversion for enhanced reservoir characterization in the Galhak Oil Formation of the Rawat Basin Sudan

Year: 2026

Type: article

Abstract: The Rawat Basin in southwestern Sudan exhibits significant hydrocarbon potential, with several structural traps successfully identified and drilled. However, the region’s exploration strategies have largely relied on conventional seismic interpretation techniques, which, despite their utility in identifying large-scale structures, lack the resolution and accuracy necessary for detailed reservoir characterization in geologically complex settings. As a result, recent drilling campaigns have yielded poor success rates, with 10 out of 13 wells proving dry. To address these challenges, this study presents an advanced Extended Elastic Impedance (EEI) inversion workflow aimed at improving subsurface prediction and reducing exploration risk. The approach integrates a comprehensive dataset, including pre-stack seismic gathers, well logs (P-wave and S-wave velocities, density, gamma ray, resistivity), and geological information. The workflow focuses on extracting rock physics attributes particularly Lame parameters (Lambda-Rho and Mu-Rho), porosity, and volume of clay that are critical for identifying prospective reservoir zones. Key methodological steps include seismic data conditioning, well-to-seismic tie, Amplitude Versus Offset (AVO) modeling, chi angle rotation, and post-stack inversion. Data preconditioning techniques such as Super Gathering, Radon Transform Filtering, and Inverse-Q filtering are applied to enhance signal-to-noise ratio, resolution, and seismic coherence. The EEI inversion results show strong correlation with well log data, confirming the robustness of the approach. Application of the method to the Galhak Oil Formation reveals well-defined fluvial and meandering channel systems associated with high-quality reservoir facies. The close agreement between inversion predictions and drilling outcomes underscores the effectiveness of this workflow for guiding future exploration and well placement in the Rawat Basin. This study represents the first application of an advanced pre-stack seismic-based Extended Elastic Impedance (EEI) inversion workflow within a Sudanese sedimentary basin. This marks a significant methodological advancement over conventional post-stack interpretation approaches previously used in the region, leading to improved reservoir prediction accuracy and more reliable delineation of prospective zones, thereby providing a stronger technical foundation for hydrocarbon exploration and development in Sudan.

Source: Scientific Reports

DOI: 10.1038/s41598-026-68052-1

Authors: Hatim Quer, Peimin Zhu, Muhammad Ali, Mohammed A. Sayed

Institutions: China University of Geosciences, Chinese Academy of Sciences, Institute of Rock and Soil Mechanics, State Key Laboratory of Geomechanics and Geotechnical Engineering

Language: English

Topic: Seismic Imaging and Inversion Techniques

Subfield: Geophysics

Field: Earth and Planetary Sciences

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $2,690

Funder: Shenzhen Fundamental Research Program