3D static reservoir modelling of the CO₂ Paleozoic Shiffah Formation in PTAH Oil Field, Western Desert (Egypt): Implications for subsurface CO₂ storage

This investigation delivers the first comprehensive evaluation of CO₂ sequestration potential within the Paleozoic Shiffah sandstone reservoir of the PTAH Field, situated in the relatively underexplored Matruh–Shushan Basin of Egypt's Western Desert. The analysis adopts an integrated, multidisciplinary approach that incorporates two-dimensional “2D” seismic interpretation, petrophysical assessment, and 3D static reservoir modeling to define the structural configuration, quantify reservoir quality attributes, and define the expected CO₂ storage volume. Structural interpretation reveals a fault-controlled horst structure featuring both three-way and four-way dip closures, offering effective lateral trapping. Concurrent stratigraphic interpretation demonstrates a thick and regionally continuous shale seal at the top of the sandstone reservoir. Petrophysical results of Shiffah sandstone show very low shale content (Vsh ≈ 0.02–0.05), elevated porosity (up to 0.117), and exceptionally high permeability (reaching 839 mD) across the crest of the horst, marking it as the most suitable interval for injection. Probabilistic storage calculations reveal an estimated capacity between 8.2 Mt (P10) and 55.4 Mt (P90) of CO₂, with the central and southern sectors exhibiting the greatest potential. The outcomes endorse a phased development strategy in which CO₂ is initially injected to enhance oil recovery, followed by permanent geological storage. Utilizing existing field infrastructure substantially lowers capital expenditure and facilitates rapid project implementation. By confirming fault-seal effectiveness, maintaining geological heterogeneity in the 3D model, and applying stringent quality-control procedures, this study reduces major uncertainties often encountered in CO₂ storage evaluation. Our results offer a reliable template for CO₂ storage initiatives across old and abandoned reservoirs, fields in north Africa and provide critical scientific insight to advance Egypt's broader decarbonization and climate-action objectives.