The Seismic Imaging and Interpretation of Faults: A Case Study from the Snøhvit Field, Barents Sea

• Main Author: Cunningham, Jennifer Elizabeth
• Other Authors: Cardozo, Nestor, Townsend, Chris
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Stavanger, University of Stavanger 2021
• Subjects: petroleumsgeologi; faults; VDP::Teknologi: 500::Berg‑ og petroleumsfag: 510::Geoteknikk: 513; VDP::Matematikk og Naturvitenskap: 400::Geofag: 450::Petroleumsgeologi og -geofysikk: 464; Barents Sea; Snøhvit
• Online Access: https://hdl.handle.net/11250/2722081

An accurate understanding of faults in the subsurface is critical to successful petroleum exploration and production. Faults define sediment distribution pathways during deposition, act as barriers or conduits to fluid flow, and can define or compromise hydrocarbon traps. Faults are commonly analysed in the petroleum industry using reflection seismic data, and more rarely core or borehole image data. Outcrop analogues are used to provide a more complete understanding of fault rock morphologies and properties. In seismic data however, faults are often imaged as discontinuities where geological horizons are vertically and horizontally displaced. Due to the limited resolution of seismic data (typically tens of metres) comparatively little can be concluded about fault morphology, internal structure or the detailed interaction of faults with seismic waves. The first paper in this thesis focuses on bridging the knowledge gap in the seismic imaging of faults by analysing how the seismic processing methods of incidence angle stacking and azimuthal separation influence fault imaging. This first paper also studies the relationship between fault orientation and seismic acquisition direction, and the impact on the seismic imaging of faults in the subsurface. The paper also demonstrates that the internal complexity of faults can influence the dominant seismic frequencies observed in and adjacent to complex fault zones. The second paper in this dissertation integrates established and newly developed analyses in fault interpretation and seismic imaging. Analyses of throw, dip distortion, seismic attributes, unsupervised fault facies and seismic amplitudes in seismic fault analysis were applied. These attributes were compared to establish the geological significance of the seismic signature in and around faults. The paper proposed a linkage between unsupervised seismic fault facies, throw and dip separation gradient which are inherently linked to the mechanical stratigraphy which controls fault propagation and growth. ...