Tectono-Stratigraphic Characterization of the Paleocene–Eocene Interval in the Upper Assam Shelf Using Integrated 3D Seismic Attribute Analysis

This study presents a high-resolution tectono-stratigraphic characterisation of the Palaeocene–Eocene Sylhet–Kopili interval on the Upper Assam Shelf using a 371.5 km² 3D post-stack time-migrated seismic volume integrated with two deep wells. Targeting the 2.5–3.5 s TWT interval, time-slices (3.048–3.200 s) combined with geometric (dip, curvature), discontinuity (similarity), and amplitude-based (reflection magnitude) attributes reveal two distinct structural domains. The north-western sector is dominated by syn-depositional normal faults forming tilted blocks and fault-bend folds, whereas the south-eastern sector is characterized by E–W to ENE–WSW sinistral strike-slip faults, S-shaped bends, relay splays, and NE–SW transfer faults that generate localized transtensional pull-apart structures. Dip and curvature attributes enhance fault-plane continuity and fault-block geometries, while reflection magnitude highlights deformation-controlled variations in reflector strength and stratigraphic contrast within the Kopili and Prang intervals. Similarity and dip-magnitude co-interpretation sharply delineate fault segmentation, linkage zones, and deformation intensity, significantly improving structural resolution compared to conventional seismic interpretation. Synthetic ties to wells W-01 and W-02 (correlation 0.6–0.72) validate key horizons and strengthen structural control. This work provides the first high-resolution 3D multi-attribute imaging of the Sylhet-Kopili interval, resolving deformation styles previously undocumented in the Upper Assam Shelf. The resulting framework delineates multiple trap geometries-tilted blocks, horsts, and fault-bend closures—and demonstrates the value of integrated dip, curvature, similarity, and magnitude attributes for improving tectono-stratigraphic interpretation in foreland basin settings.