Integrated Analysis of Sequence Stratigraphy, Seismic Interpretation and Petrophysical Data for Cenomanian Reservoirs (Horus Field, Alamein Basin, Egypt): Implications for Siliciclastic/Carbonate Reservoir Distribution and Quality

ABSTRACT

This study integrates seismic interpretation, sequence‐stratigraphic analysis and petrophysical evaluation to characterise the Cenomanian hydrocarbon potential within the Bahariya Formation and Abu Roash ‘G’ Member at Horus Field, Alamein Basin. Seismic interpretation revealed ENE–WSW and ESE–WNW trending extensional normal faults, forming structural highs (horsts, tilted blocks) that act as primary hydrocarbon traps. The Abu Roash Formation exhibited the highest seismic reflector continuity, aiding robust structural mapping, while the underlying Bahariya, Kharita and Alam El Bueib formations showed increasing discontinuity downwards. Instantaneous Amplitude and Energy attributes were applied to quantitatively show deeper‐layers amplitude decay, reflector continuity and reveal subtle stratigraphic geometries obscured in conventional seismic data. Sequence stratigraphic analysis delineated two depositional sequences. BAHR‐SQ‐1 (Bahariya Fm), a siliciclastic‐dominated sequence (535–640 ft), comprises Lowstand (LST‐1: fluvial‐deltaic to shallow marine sandstones), Transgressive (TST‐1: mixed siliciclastics/carbonates) and Highstand (HST‐1: progradational sandstones) Systems Tracts. ARG‐SQ‐2 (Abu Roash ‘G’ Member; 525–675 ft), a carbonate/siliciclastic sequence, comprises a Transgressive Systems Tract (TST‐2: deep‐shelf dolomites) and a Highstand Systems Tract (HST‐2: progradational mixed facies). Petrophysical assessment identified both sequences as hydrocarbon‐bearing reservoirs but with distinct characteristics. The Upper Bahariya (HST‐1) offers volumetric potential (thickness 220–233 ft., porosity 29%–35%) but exhibits variable, generally poorer quality (lower net‐to‐gross: 2%–12%, higher shale volume: 15%–25%, higher water saturation: 32%–33%, limited pay: 4–29 ft). In contrast, the Abu Roash ‘G’ Dolomite (primarily TST‐2) demonstrates superior and consistent reservoir quality across wells (thickness 60–81 ft., net‐to‐gross: 15%–32%, lower shale volume: 5%–9%, porosity 21%–24%, lower water saturation: 28%–41%, hydrocarbon saturation 59%–73%, pay 12–23 ft). The cleaner lithology and favourable petrophysics make the Abu Roash ‘G’ the key contributor to hydrocarbon potential, despite its lesser thickness compared to the Bahariya. These results underscore the critical control of sequence stratigraphic architecture and depositional facies on reservoir distribution and quality, providing essential insights for future exploration targeting in analogous settings.