Fluid Leakage Classification and Analysis in the SW Barents Sea

Stefan Buenz, Sunil Vadakkepuliyambatta, and Juergen Mienert
Department of Geology, University of Tromsø, Tromsø, Norway.

The vertical flow of fluids through marine sediments is a widespread and dynamic geological process that occurs on passive and active continental margins worldwide. Fluid leakage is associated with excess pore-fluid pressure and attributed to temporally and spatially varying processes such as rapid sediment loading, uplift and erosion, dissociation of gas hydrate, polygonal faulting and hydrocarbon generation and leakage from deep and shallow reservoirs. The SW-Barents Sea is a part of Arctic Ocean located north of Norway. The occurrence of shallow gas, gas hydrates and seafloor expulsion features is reported from several areas of the SW Barents Sea. Leakage of fluids into the shallow sediments and into the ocean through the seafloor was probably the result of the profound Cenozoic erosion of the Barents Sea shelf during various glaciations. The flow of these fluids through marine sediments may have controlled the evolution of the various sedimentary basins of this region. For a better understanding of the fluid flow features, their timing and origin, we here analyze approximately 3000 2D seismic profiles from different basins of the SW Barents Sea to identify different features of fluid leakage, classify them and study their relation to the structural elements and geological history of the SW Barents Sea.

We analyzed 2D seismic data from different basins of the SW Barents Sea to identify different fluid-flow features, classify them and study their relation to structural elements and geological history of SW Barents Sea. Most of the identified features fall in the category of gas chimneys and leakage through faults and fractures. Several complex fluid-flow features, a combination of chimneys and faults, were quite common suggesting a relation between the occurrence of faults and fluid leakage. Among the various observed fluid flow features were: giant gas chimneys covering large areas, vertical blow-out pipes, pockmarks, buried collapse structures, fluid leakage along polygonal faults, sediment mobilization and fluid leakage, and high amplitude anomalies due to the trapped fluids. The fluid leakage features show good relation to the structural setting of the SW Barents Sea. Most of the fluid flow features coincide with major faults in the SW Barents Sea suggesting a relation between fluid flow and deep seated faults and indicate leakage from Jurassic and older formations. The number of fluid flow features in the western part of the study area was significantly higher than the eastern part. Since they are related to the structural elements in the region, the tectonic activity and glacial cycles would have significantly affected the hydrocarbon accumulation and migration. The amount of erosion in the area is found to have no direct relation to the distribution of fluid flow features.

AAPG Search and Discovery Article #90130©2011 3P Arctic, The Polar Petroleum Potential Conference & Exhibition, Halifax, Nova Scotia, Canada, 30 August-2 September, 2011.