HR: 0800h
AN: S51B-06    [Abstracts]
TI: Seismic Imaging of Focused Fluid-Flow-Related Pipe Structures; a Case Study at the Mid- Norwegian Margin
AU: * Hustoft, S
EM: steinar.hustoft@ig.uit.no
AF: University of Tromso, Department of Geology, Dramsveien 201, Tromso, 9037, Norway
AU: Bunz, S
EM: stefan.buenz@ig.uit.no
AF: University of Tromso, Department of Geology, Dramsveien 201, Tromso, 9037, Norway
AU: Planke, S
EM: planke@vbpr.no
AF: Volcanic Basin Petroleum Research AS, Forskningsparken, Gaustadalleen 21, Oslo, 0349, Norway
AU: Mienert, J
EM: jurgen.mienert@ig.uit.no
AF: University of Tromso, Department of Geology, Dramsveien 201, Tromso, 9037, Norway
AB: The project entitled "Quantification of geological processes that govern basin-scale fluid flow" within the PETROMAKS-project financed by the Norwegian Research Council aims to understand the complexity of fluid- flow processes. Focussed fluid flow processes are expressed in a multitude of seismic signatures and structures observed on the Mid-Norwegian margin. Here, we study the Nyegga-area located close to the Storegga slide and at the border of two large oil- and gas-prone sedimentary basins, the Møre- and Vøring Basin. Multibeam bathymetry data and conventional 3D-seismic data demonstrate hundreds of pockmarks at the seabed and corresponding acoustic pipe structures in the subsurface. These features are undoubtedly caused by focusing of fluids, but what are the geological processes and what contributes to their appearance on seismic data? Increased seismic energy response from the pockmarks may stem from precipitated authigenic carbonates and/or gas hydrates within the near-surface sediments. Seismic data indicate semi-circular near- vertical geometry of the pipe structures, contained by low amplitude pull-up reflections towards the central zone. The pipe structures varies in size, but commonly the larger the pockmark the wider and deeper the pipe structure. The pipe structures have an apparent depth of 300-600 meters, but additional pipe structures may be rooted as deep as 1000 mbsl, and hence, pierce the whole Miocene-Pleistocene succession. We compare conventional 2D- and 3D-seismic data with medium and high resolution single-channel data to investigate internal acoustic characteristics of individual pipe structures. Single-channel data and near-offset data reveal an acoustic turbidity within pipe structures that apparently are related to scattering of seismic energy from the pockmarks. To investigate the deeper internal pipe characteristics we conduct the undershooting technique to improve the seismic imaging of the pipes below the complex pockmark sites. This technique involves shot-domain elimination of all traces with ray-paths travelling through the pockmark, followed by a standard processing work flow. The finite undershot stack-section improves seismic imaging of focussed fluid flow pathways due to eliminating surface-generated acoustic signatures at the pipe structures.
DE: 3002 Continental shelf and slope processes (4219)
DE: 3004 Gas and hydrate systems
DE: 8003 Diapir and diapirism
DE: 8169 Sedimentary basin processes
SC: Seismology [S]
MN: 2007 Joint Assembly