Natural Gas Venting in the Tampen Area, Northern North Sea: Insights from Subsurface and Glacial Interactions

The Tampen area, located along the western bank of the Norwegian Channel in the northern North Sea, is a region of significant natural gas venting activity. Understanding seepage mechanisms here, is however challenging due to subsurface lithological heterogeneity caused by glacial erosion and deposition, as well as acoustic disturbances beneath the seepage zones.

To address these challenges, we conducted a detailed subsurface investigation using high-resolution 3D seismic data that revealed bright amplitude anomalies concentrated beneath the seepage sites that relate to two distinct depocenters hosting high-porosity sediments that act as reservoirs for trapped gas.

The primary depocenter exhibits a wedge-shaped geometry, with bright anomalies arranged in a delta-like pattern. The secondary depocenter is associated with a single, large glacial lineation near the bank area, forming a cavity filled with fine to coarse sediments. We propose a conceptual model outlining a series of geological events that began around 30 ka BP. During a relative sea-level low stand (~25–30 ka BP), significant sandy deposits accumulated, which were later submerged during subsequent high stands. This was followed by the advance of ice sheets, which contributed to extensive glacial erosion and deformation of these deposits. Additionally, the sediments infilling the glacial lineation are attributed to an ice-dammed lake outburst event that occurred during the collapse of grounded ice across the North Sea shelf after the Last Glacial Maximum (LGM).

Fluid escape pathways are mainly along the wedge's western boundary, where eastward-dipping sandy beds aid upward migration. Gas seepage is influenced by glacial deformation and the thickness and distribution of lateral moraines.

This study highlights the interplay between glacial processes, subsurface lithology, and fluid migration in shaping natural gas venting in the Tampen area. The continuous seepage in this narrow corridor underscores the importance of understanding its impact on climate change and the risks it poses for drilling in sensitive environments.