3D-Seismic investigation of Fluid Flow and Faulting in the western margin of the SW Barents Sea, southern Sørvestsnaget Basin along the Senja Ridge

Abstract

The southwestern Barents Sea margin has attracted growing interest due to its hydrocarbon potential. However, the dynamics of its shallow subsurface fluid systems remain poorly understood. This thesis investigates fluid migration, faulting, and shallow gas accumulations within the southern Sørvestsnaget Basin adjacent to the Senja Ridge, using high-quality 3D seismic data (Carlsen3D) in combination with well data from 7117/9-1, 7117/9-2, 7216/11-1S, and 7218/11-1T2.

Through seismic interpretation, structural mapping, and amplitude analysis, a range of fluid flow features are identified, including high-amplitude anomalies, bright spots, acoustic chimneys, and zones of seismic masking. These features are primarily concentrated within the glacigenic Naust Formation and are closely associated with deep-seated faults, polygonal fault systems, and salt-related structures. The salt have significantly deformed the overburden, promoting the development of structural traps, fault-assisted migration pathways, and shallow gas accumulations.

Observed fluid flow range from confined accumulations beneath regional unconformities to active vertical migration terminating at the seafloor. Clear spatial relationships between faults, amplitude anomalies, and seafloor depressions suggest that fault networks provide conduits for hydrocarbon fluids. Salt diapirs appear to play a central role in accommodating vertical migration by deforming and fracturing the overburden. Glacial-interglacial cycles likely triggered fault reactivation and fluid remobilization, resulting in seafloor deformation and fluid expulsion.

These findings highlight the complex interplay between halokinesis, fault systems, and glacial processes in shaping fluid plumbing systems in the region. The results offer insights into the behavior of shallow gas systems and contribute to the broader understanding of the SW Barents Sea margin shallow gas systems.