Fine characterization and favorable zone prediction of mid-deep fluvial thin interbedded sand bodies in offshore areas: A case study of H1—H2 layers in Z gas field

Precise reservoir characterization holds critical significance for portraying structural-lithological exploration targets, yet presents substantial geophysical challenges when dealing with thin interbedded layer configurations. We conducted an integrated research into regional sedimentology, and defined facies types with high-resolution seismic inversion techniques, by which thin reservoir identification capabilities were enhanced. Based on region-wised seismic interpretation, we established the isochronous stratigraphic framework of the study area, and analyzed the seismic sedimentology by extracting representative plan-view seismic attributes to delineate lateral reservoir distribution. Subsequent integration of fault architecture, structural configuration, and reservoir heterogeneity characteristics helped comprehensive evaluation of potential exploration targets. Results demonstrate a fluvial-dominated depositional system featuring three sandbody patterns: sheet type (extensive continuous distribution), dendritic type (branching networks), and ribbon type (linear channel belts). Particularly, the sheet type meandering sandbodies exhibit superior hydrocarbon accumulation potential, characterized by optimal fault-sand coupling relationships, proximity to petroleum-source faults, and strategic positioning within structural highs. The developed methodology established a novel geologic-seismic fusion workflow for thin interbedded reservoir prediction, providing a valuable reference for reservoir characterization in analogous depositional systems, particularly in the areas where complex stratigraphic architectures challenge conventional exploration approaches.