Controls on Shelf-Margin Architecture and Deep-Water Sand Delivery in Contrasted Climatic and Tectonic Settings: Insights from Quantitative 3D Seismic Stratigraphy

With ~15% of siliciclastic hydrocarbon reservoirs located in deep-water basins, a key challenge is to predict when and where sands are bypassed to deep-water areas, and how they are architecturally organized. Quantitative 3D Seismic Stratigraphy (QSS) aims at investigating the linkages between hydrodynamic regime along paleoshorelines, shelf-margin architecture and the development of coeval deep-water systems in a variety of tectonic and climatic settings. Results confirm that low values of rate of accommodation / rate of sediment supply (δA/δS) on the shelf are associated with sediment bypass, whereas high δA/δS conditions are linked to increasing sediment storage on the shelf. However, coastal process regimes at the shelf edge play a more important role in the deep-water sand delivery behaviour. While any type of paleoshoreline or deep-water system can be developed under any δA/δS condition, fluvial-dominated shorelines are typically associated with: (1) slope gradients twice steeper than the wave-dominated shorelines; and (2) longer run-out turbidite systems. In contrast, wave-dominated shorelines are linked to gentle slope gradients, with limited turbidite system development (except rare sheet sands and mass-transport deposits). Results also reveal that tide-dominated processes play a transition role between wave- and fluvial-dominated shorelines, where tide-dominated processes are associated with short run-out turbidite systems. By integrating advanced tools in seismic interpretation, quantitative 3D seismic stratigraphy represents a novel approach in assessing at high resolution the controls on deep-water sand delivery, and potentially predicting the type and location of reservoirs in deep water based on shelf-margin architecture and depositional process regime.