Crestal fault geometries reveal late halokinesis and collapse of the Samson Dome, Northern Norway: Implications for petroleum systems in the Barents Sea

• Published in: Tectonophysics 2016-10, Vol.690, p.76-96
• Main Authors: Mattos, Nathalia H., Alves, Tiago M., Omosanya, Kamaldeen O.
• Format: Article
• Language: English
• Subjects: Barents Sea; Collapse; Cretaceous; Faults; Fluid-flow; Geometry; Halokinesis; Hydrocarbons; Kinematics; Natural gas; Natural gas exploration; Offshore; Offshore drilling rigs; Oil and gas exploration; Oil exploration; Petroleum; Salt collapse; Salts; Samson Dome; Segments; Seismic surveys; Structures; Studies; Tectonic stress; Triassic
• ISSN: 0040-1951; 1879-3266
• DOI: 10.1016/j.tecto.2016.04.043

This paper uses 2D and high-quality 3D seismic reflection data to assess the geometry and kinematics of the Samson Dome, offshore Norway, revising the implications of the new data to hydrocarbon exploration in the Barents Sea. The study area was divided into three (3) zones in terms of fault geometries and predominant strikes. Displacement-length (D-x) and Throw-depth (T-z) plots showed faults to consist of several segments that were later dip-linked. Interpreted faults were categorised into three families, with Type A comprising crestal faults, Type B representing large E-W faults, and Type C consisting of polygonal faults. The Samson Dome was formed in three major stages: a) a first stage recording buckling of the post-salt overburden and generation of radial faults; b) a second stage involving dissolution and collapse of the dome, causing subsidence of the overburden and linkage of initially isolated fault segments; and c) a final stage in which large fault segments were developed. Late Cretaceous faults strike predominantly to the NW, whereas NE-trending faults comprise Triassic structures that were reactivated in a later stage. Our work provides scarce evidence for the escape of hydrocarbons in the Samson Dome. In addition, fault analyses based on present-day stress distributions indicate a tendency for ‘locking’ of faults at depth, with the largest leakage factors occurring close to the surface. The Samson Dome is an analogue to salt structures in the Barents Sea where oil and gas exploration has occurred with varied degrees of success. •3D seismic data are used to reassess the geometry and kinematics of the Samson Dome.•Faults crossing the dome were initiated in the Triassic and reactivated in several stages.•Faults show a tendency to ‘lock’ at depth under present-day stress conditions.•Samson Dome is a smaller seepage structure than previously proposed.