Cenozoic basin evolution and petroleum system characterization within the Tangier 3D seismic survey, central Scotian Slope, Canada

Abstract

Undiscovered hydrocarbon reservoirs potentially exist in the deep-water regions of the Scotian Margin off the coast of Nova Scotia. The deep-water environments can involve major challenges with high exploration risk because the presence, quality, size, and distribution of source and reservoir rocks are still relatively unknown for many areas. Using the Tangier 3D Seismic Survey, seismic interpretation and attribute analysis within the Cenozoic was conducted. The results show the region hosts a complex subsurface geology with modern-day and paleo-channels and canyons, contourite sediment drifts, slope failure complexes, and proglacial slope drapes. Salt-related structural features, which occur deeper than 3 km in the basin, include welds, wings, feeders, pedestals, rollers, withdrawal minibasins, rafted overburden, and growth and crestal faults. Also observed within the Tangier 3D area are three shallow-level amplitude anomalies interpreted to be direct hydrocarbon indicators (DHIs). The DHIs situated above diapirs and a salt canopy strongly indicate the presence of migrating fluids. The architectural investigation of these DHIs provides evidence of a working petroleum system governed by salt mobility, which provides migration pathways for the more deeply sourced fluids. However, further study is needed to determine if the fluids filling these DHIs are thermogenic hydrocarbons that escaped from deeper Jurassic or Cretaceous sources and breached reservoirs.