Hydrocarbon leakage above the Snohvit gas field, Hammerfest Basin SW Barents Sea

摘要

Analysis of high resolution 3D seismic reflection data from the Snahvit and Albatross gas fields has provided insights into the nature and dynamics of the fluid flow plumbing system in the Hammerfest Basin. The area investigated is characterized by a high density of pockmarks up to 300 m wide, as well as giant pockmarks over 1 km wide, linked to regional faults and seismically defined chimneys. Thermogenic gas hydrates are inferred from the presence of a bottom-simulating reflector, while the fluids are thought to be sourced through regional tectonic faults from the deep reservoirs. Evidence of glacial erosion processes suggests that the focused fluid escape took place during the ice retreat on two separate occasions, when the pockmarks and seismic pipes are thought to have been formed by methane leakage from the decomposition of gas hydrates. This evidence of large numbers of fluid flow structures may indicate potential geohazards for future exploration, development, and carbon dioxide sequestration in the greater Snehvit area. Our results may be used as an analogue for other glacially influenced areas where hydrocarbon leakage is a major risk.